Main Changing Body Composition through Diet and Exercise

Changing Body Composition through Diet and Exercise

Year: 2016
Publisher: The Teaching Company
Language: english
Pages: 250
Series: The Great Courses
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Topic
Better Living

Subtopic
Health & Wellness

Changing Body
Composition through
Diet and Exercise
Course Guidebook
Professor Michael J. Ormsbee
Florida State University

PUBLISHED BY:
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Copyright © The Teaching Company, 2016

Printed in the United States of America
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Without limiting the rights under copyright reserved above,
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or introduced into a retrieval system, or transmitted,
in any form, or by any means
(electronic, mechanical, photocopying, recording, or otherwise),
without the prior written permission of
The Teaching Company.

Michael J. Ormsbee, Ph.D.

Assistant Professor in Nutrition,
Food, and Exercise Sciences
Florida State University

D

r. Michael J. Ormsbee is an
Assistant
Professor
in
the
Department of Nutrition, Food,
and Exercise Sciences and the Interim
Director for the Institute of Sports Sciences
and Medicine at Florida State University
(FSU). He is a faculty affiliate of the Center
for Advancing Exercise and Nutrition Research on Aging and the Institute
for Successful Longevity at FSU. Dr. Ormsbee is also an Honorary Research
Fellow at the University of KwaZulu-Natal in Durban, South Africa. He earned
his B.S. in Exercise Science and Business from Skidmore College, his M.S. in
Exercise Physiology and Sports Nutrition from South Dakota State University,
and his Ph.D. in Bioenergetics from East Carolina University. Dr. Ormsbee’s
research and expertise involve the interaction of exercise, nutrition, and
supplementation to achieve optimal body composition, human performance,
and health in both athletes and clinical populations.
Prior to arriving at FSU, Dr. Ormsbee taught and conducted research
at Skidmore College. His major research contributions have included
investigation into meal composition and frequency, exercise type and
duration, nighttime feeding, and the use of supplements to alter body
composition and performance. Dr. Ormsbee started Ormsbee Fitness
Consulting in 2006 and has worked with everyone from Olympic athletes
to everyday people. He is a sought-after speaker both nationally and
internationally on issues related to exercise, diet, and performance nutrition.
While at FSU, Dr. Ormsbee won the 2013–2014 University Teaching Award,
the Excellence in Online Course Design Award, the Excellence in Online
Teaching Award, and the 2013 Transformation through Teaching Award. He
i

Changing Body Composition through Diet and Exercise

was also selected for the Guardian of the Flame Faculty Award by the Burning
Spear leadership honor society in 2015. In 2012, Dr. Ormsbee was elected as
a Fellow of the International Society of Sports Nutrition, and in 2014, he was
elected as a Fellow of the American College of Sports Medicine.
Dr. Ormsbee regularly publishes his research in the top scientific journals in
his field and presents at national and international conferences. He is active
in education and outreach, giving seminars to academics, athletes, and
the public. Dr. Ormsbee and his work have been featured in many popular
magazine, radio, podcast, and television outlets, including The Washington
Post, Men’s Health, Shape, Philly.com, and O, The Oprah Magazine. ■

ii

Table of Contents
INTRODUCTION
Professor Biography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Course Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

LECTURE GUIDES
LECTURE 1

Body Composition: Managing Our Expectations. . . . . . . . . . . . . . . 3
LECTURE 2

A Healthier Way to Measure Body Composition. . . . . . . . . . . . . . . 11
LECTURE 3

How Food Is Digested and Absorbed. . . . . . . . . . . . . . . . . . . . . . . 20
LECTURE 4

Nutritional Needs and Cellular Function. . . . . . . . . . . . . . . . . . . . . 28
LECTURE 5

Bioenergetics: Converting Food to Energy. . . . . . . . . . . . . . . . . . . 37
LECTURE 6

Carbohydrates: Composition, Storage, and Use. . . . . . . . . . . . . . . 44
LECTURE 7

Fat: Not the Nutritional Bad Guy. . . . . . . . . . . . . . . . . . . . . . . . . . 52
LECTURE 8

Protein’s Critical Role in Body Composition . . . . . . . . . . . . . . . . . . 60
LECTURE 9

High-Protein Diets and Anabolic Resistance. . . . . . . . . . . . . . . . . . 69
iii

Changing Body Composition through Diet and Exercise

LECTURE 10

Critical Micronutrients and Water . . . . . . . . . . . . . . . . . . . . . . . . . . 78
LECTURE 11

Food Labeling and Nutritional Choices. . . . . . . . . . . . . . . . . . . . . . 87
LECTURE 12

Nutrient Timing and Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
LECTURE 13

Nighttime Eating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
LECTURE 14

Evaluating Dietary Supplements. . . . . . . . . . . . . . . . . . . . . . . . . . 110
LECTURE 15

Energy Balance and Weight Control. . . . . . . . . . . . . . . . . . . . . . . 119
LECTURE 16

The Caloric Cost of Exercise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
LECTURE 17

Exercise for Fat Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
LECTURE 18

Exercise for Healthy Muscle Mass. . . . . . . . . . . . . . . . . . . . . . . . . 142
LECTURE 19

Hormones and Body Composition . . . . . . . . . . . . . . . . . . . . . . . . 149
LECTURE 20

Novel Ways to Change Body Composition. . . . . . . . . . . . . . . . . . 157
LECTURE 21

Nutrition and Exercise: Special Needs . . . . . . . . . . . . . . . . . . . . . 166
LECTURE 22

Set-Point Theory and the Last Five Pounds. . . . . . . . . . . . . . . . . . 173

iv

Table of Contents

LECTURE 23

Choosing Your Nutrition Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
LECTURE 24

Motivation to Change Your Body Composition. . . . . . . . . . . . . . . 190

SUPPLEMENTAL MATERIAL
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Image Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

v

Disclaimer
This series of lectures is intended to convey general health, fitness, and
nutritional information and is for educational purposes only. It is not a
substitute for, nor does it replace, professional medical advice, diagnosis,
or treatment of health conditions. Please consult your physician or other
health-care professional before beginning or changing any fitness or nutrition
program to make sure that it is appropriate for your needs. If you have
any concerns or questions about your health, you should always consult a
physician or other health-care professional. Do not disregard, avoid, or delay
obtaining medical or health-related advice from your health-care professional
because of something you may have seen or heard in these lectures. Current
health and fitness research may exist that could affect the educational
information provided in these lectures, and advice found herein may not be
based on the most recent findings or developments. Therefore, the use of any
information provided in these lectures is solely at your own risk. By continuing
with the programs, exercises, advice, information, or diets discussed in these
lectures, you recognize that there are risks of injury or illness that can occur
because of your use of the aforementioned information, and you expressly
assume such risks and waive, relinquish, and release any claim that you may
have against The Teaching Company as a result of any future physical injury
or illness incurred in connection with, or as a result of, use or misuse of the
programs, exercises, advice, diets, and/or information discussed in these
lectures. The opinions and positions provided in these lectures reflect the
opinions and positions of the relevant lecturer and do not necessarily reflect
the opinions or positions of The Teaching Company or its affiliates.
The Teaching Company expressly DISCLAIMS LIABILITY for any DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR
LOST PROFITS that result directly or indirectly from the use of these lectures.
In states that do not allow some or all of the above limitations of liability,
liability shall be limited to the greatest extent allowed by law.

vi

Acknowledgments
Sam Kramer
Brittan Allman
Katie Gorman
Stacy Cappadona
Amber Kinsey
Palmer Johnson
Chris Bach
Morgan Clift
Beth Miller

vii

viii

Changing Body Composition through
Diet and Exercise
Scope

I

mproving body composition by losing body fat and optimizing lean
muscle mass is not about vanity—it’s about health. It’s not about how
quickly you can lose weight or how small you can become. It’s about
how to become stronger and healthier while decreasing your body fat and
increasing your muscle mass. It’s about changing your body composition
through diet and exercise in a safe way that supports you holistically and
helps you achieve optimal health and performance. This course is about the
science of nutrition and exercise that can lead to lasting changes in body
composition.
In the first section of the course, you will learn why body weight is not the
best way to determine your health status and why understanding more
about exactly how much body fat you have and how much muscle mass
you have is the key to improved health and performance. You will discover
what happens to food from the moment it enters your mouth—where it
goes and how it supports your cellular functions. You will learn about what
carbohydrates, fats, and proteins are and how they are broken down in your
body to provide energy for everything you do. You will also discover that as
you age, your nutrition needs change.
The next part of the course explores how to evaluate a nutrition label, and
you’ll discover that the calories from a bag of chips are entirely different
from the same number of calories from a piece of fruit or lean meat. You’ll
consider how not only your food choices, but also when you eat and how
frequently you eat might influence how you feel, look, and perform day to
day in your normal life and also while you exercise. You’ll also uncover myths
and facts about dietary supplements that are designed to help you lose
1

Changing Body Composition through Diet and Exercise

body fat or gain muscle mass all within the context of energy balance and
weight control.
The third segment of the course examines the caloric cost of exercise, and
you’ll learn some simple strategies that help increase your activity level. You
will discover why certain types of exercise might be most beneficial for losing
body fat or gaining muscle mass. This section allows you to draw conclusions
for the most optimal way for you to incorporate various types of exercise into
your life to meet your goals. You’ll also discover why weight training is good
for everyone and won’t just make you big and bulky. You will also explore
certain hormones and the influence they have on your body composition.
The final lectures will use science to dispel myths about unrealistic methods
that are marketed to improve body composition and provide evidence for
what really works. You’ll also discover the best practices for handling travel,
boredom, and a busy schedule while keeping your nutrition and workout
plan consistent. You will learn why improvements in body composition tend
to plateau and how the set point influences your outcomes. You’ll discover
the science behind popular diets and how to build sustainable habits for
successful loss of body fat and gain in muscle mass.
By the end of this course, you will learn to avoid the quick-fix mentality and
find simple strategies to keep discipline, hard work, and fun in your plan to
improve body composition. You will appreciate the complexity of the human
body and understand why smart nutrition and purposeful exercise are both
critical for improving body composition, health, and performance.

2

Lecture 1

Body Composition: Managing Our
Expectations

T

his course is about the science of nutrition and exercise that can lead
to changes in body composition. The goal of the course is to provide
you with the tools to make the decisions that you want to make, when
you want to make them, to produce lasting results, not necessarily fast
results. This course will provide you with all of the information you need to
make big or small changes to live a fit life. The field of nutrient metabolism,
exercise physiology, body composition, and performance—also known as
performance nutrition—involves studying how energy is derived from foods
and how this energy fuels exercise and human movement.

Body Composition
„„

What is body composition, and why should it be used as your indicator
of health instead of body weight? We all get crazy about body weight
when what we should be talking about instead is how much muscle and
how much fat we have. A two-pound fat loss and a two-pound gain in
muscle would improve your body composition, health, and functionality,
but it would not change your body weight.

„„

Body mass index (BMI), which is your weight in kilograms divided by your
height in meters squared, is useful in some situations but not others.
The way you hold your weight—how much fat and how much muscle
you have—contributes a lot to how you look, feel, and perform (in the
context of the real world—in your job, with your family, and with your
general energy and enthusiasm for life—not simply on an athletic field).

„„

The nutrition that feeds your body and fuels the physical activity that
can change your body composition is also a major component of the
3

Changing Body Composition through Diet and Exercise

science of body composition. Nutrition is directly linked to your health
and well-being. It influences your body composition and your energy
levels for work, play, and exercise.

Energy Balance
„„

A lot of controversy surrounds the topic of energy balance. Energy
balance is the balance of the calories you take in from foods and
beverages (energy intake) with the calories that you expend (energy
output) for all of your biological processes necessary to live, such as
breathing and thinking, plus the calories you expend from walking
around and from exercise.

„„

To alter body composition, to lose fat (for example), you want an energy
deficit. Just burn more than you take in. But if it were that easy, maybe
we wouldn’t have the obesity epidemic that we have today.

„„

The quality of our calories has as much of an impact on our body
composition and overall health as the total number of calories that we

4

Lecture 1—Body Composition: Managing Our Expectations

eat daily. Your body needs certain foods. In fact, you should probably eat
more protein in your diet. Your body works harder to digest and absorb
protein than it does carbohydrates and fats. This is probably why eating
protein gives you the largest increase in metabolism when you eat it.
„„

A number of research studies have been designed to measure
metabolism after a meal containing protein versus fat versus
carbohydrates, and the majority of these indicate that the greatest
impact on increasing metabolism comes after eating protein. Some
foods come with a little bit of a metabolic advantage, and this can have
an impact on goals you’re setting for changing body composition.

„„

Twenty years ago, we were served smaller portion sizes. The National
Institutes of Health tells us that a bagel 20 years ago was typically
around 3 inches in diameter and 140 calories. Today, a bagel is typically
6 inches in diameter and contains nearly 350 calories—more than twice
as many calories as just 20 years ago.

„„

You don’t have to begin counting calories, because that takes a lot of
time and is not fun. Getting bogged down with the numbers complicates
it all and can get you fixated on the wrong kinds of details. Instead, try
using your hands as a way to gauge how much you should eat.

„„

For example, most women can go with one palm-sized portion of lean
protein to meet their needs at a particular meal. Men, who typically have
bigger and thicker hands, can go with two palm-sized portions of lean
protein. You simply adjust this based on your goals and the food you
are eating. Carbohydrates, for example, could be a fist-sized portion of
vegetables or rice.

„„

Learning to pay attention to what you eat and how you feel will help you
achieve your optimal body composition and lead to improved health and
performance. When you eat, just eat. If you’re distracted while you eat—
rushed, or stressed, or not paying attention—you are more likely to eat
more than your body really wants or needs. Most of the time, the simple

5

Changing Body Composition through Diet and Exercise

practice of eating just enough becomes overcomplicated by massive
amounts of media propaganda, misinformation, or family habits.

Exercise
„„

How much exercise do you need to do, and how often do you need to
do it? What exercise or activity works best if you want to gain muscle
mass, and what works best if you want to lose fat?

„„

Data shows that we lose about 5 percent of our muscle mass per decade.
Over the span of 50 years, you could lose as much as 25 percent of your
muscle mass. That’s not something we want. It can make you weak and
frail and lower your metabolism a lot, too.

„„

But the fact is that the overall decrease in your metabolism is only one
to three percent during the aging process, which really doesn’t amount
to much—and you can easily offset this with the nutrition and exercise
strategies that you’ll learn throughout this course.

„„

Many people think that being sedentary is easier than being active. Screen
time—the time that people watch television, use the Internet, play video
games, or look at their phones—is increasing every year. This is likely a big
problem because during these activities, we’re usually not moving.

„„

In a national sample of girls and boys, it was found that those who
watched less than two hours of television per day had about a 10
percent chance of becoming obese, but those who watched more than
five hours per day had close to a 30 percent chance of becoming obese.

„„

For adults, this is also an issue—typically from too much sitting and
sedentary time during the day. In fact, a number of research studies
link daily sitting time to a number of health concerns, including risk of
obesity, cardiovascular disease, and cancer.

„„

The obvious answer is to exercise. Unfortunately, planned exercise and
unplanned activity typically slow down as we age and make it likely for

6

Lecture 1—Body Composition: Managing Our Expectations

us to gain weight and fat. You need to make a real effort to stop this
reduction in metabolism and work for your optimal body composition.
„„

Having the body composition of your dreams is certainly a great goal,
but keep in mind that just being active is extremely helpful for improving
your health. The good news is that following even the most basic of
recommendations brings many benefits.

„„

In fact, just a 5 to 10 percent loss in total body weight will improve
your blood pressure, cholesterol, and sugar levels. And even if you’re
still in the “overweight” or “obese” range, this modest weight loss can
decrease your risk factors for chronic diseases related to obesity.

„„

A major point of information about body composition that most people
don’t know is that if you are trying to lose weight, you should be lifting
weights. This might go against what you’ve always been told, but long
and slow aerobic exercise is no longer the recommended way to lose fat.
While it is part of the plan, many other types of exercise are needed if you
really want a fighting chance to lose fat but keep or add muscle mass.

„„

Particularly when trying to lose weight, it’s important to lift weights so
that your muscle mass has the best chance of staying around and your
metabolism stays as high as possible.

„„

Quick changes in body composition should not be expected. Instead,
look for changes to come over a period of time, after you’ve dialed in
a nourishing eating plan based on quality foods and a consistent and
effective exercise regimen.

Nutrition
„„

Overall, the health benefits of exercise and eating right are clear. If a
pill existed with even half of the same benefits, there’s no doubt that it
would be the best seller.

7

Changing Body Composition through Diet and Exercise

8

Lecture 1—Body Composition: Managing Our Expectations

„„

Even if you are overweight or obese, simply being physically active can
ward off metabolic disease and keep you healthy. Health is not always
about weight. Of course, they are related, but the key for your health is
that you exercise and work on ways to improve how you eat.

„„

However, simply exercising more and eating less is not the key for
improving body composition. We’ve been preaching this for a long time,
but it doesn’t work very well. The science of healthy body composition
is not weight loss science; it’s the science of a healthy balance of fat and
muscle mass and how we can achieve that.

„„

Choosing both quality exercise and quality foods is the way to make
lasting improvements. And weight loss might be a consequence of
changing eating and exercise habits, but it is not the goal.

„„

It’s also important to keep in mind that things like your genetics, your
environment, and even chemical pollutants are factors that might
contribute to gaining fat. But even though our ability to alter our body
composition depends on many things, the take-home message is that
exercise and quality nutrition do a body good.

„„

In fact, exercise and nutrition must be combined for a healthy body
composition. You can make it pretty far with one or the other, but
healthy does not just mean “not overweight.”

„„

Your journey to better health is not about a quick fix; it’s about a
lifestyle change that works for you. It’s not about how quickly you can
lose weight or how small you can become. It’s about how to become
stronger and healthier while lowering your body fat and increasing your
muscle mass. It’s about changing your body composition through diet
and exercise in a safe way that supports you holistically and helps you
achieve more day to day.

9

Changing Body Composition through Diet and Exercise

Try This
Write down the biggest hurdle you see as standing in the way of
achieving your optimal body composition and health.

Questions to Consider
1. What is the easiest and most sustainable change that you think
you can make for big improvements in your body composition,
health, and performance?
2. What exercise or nutrition myth was busted by this lecture?

10

Lecture 2

A Healthier Way to Measure Body
Composition

B

ody weight offers no indication of how much fat versus muscle a
person carries on his or her frame. This relative proportion is critical,
because it is related to what the status of our overall health is, how our
body moves and behaves, and how we look and feel aesthetically. How can
we better quantify success with weight management? After this lecture, you
will have a better, healthier idea of what’s happening to your body during
weight loss, which benchmarks are typically used to indicate success, and
why success goes far beyond simply what the scale tells you.

Body Mass Index and Fat-Free Mass Index
„„

Body mass index (BMI) compares your body weight (in kilograms) to
your height (in meters squared). A note of caution: Measures like BMI or
body weight may be relevant only in certain situations. The usefulness
of BMI is not great when considered on an individual-to-individual basis.
In practice, BMI is most appropriate for large sample populations or in
a clinical situation to quantify risk for a patient who is clearly overweight
and overfat at the same time.

„„

There are four main categories of BMI.
‹‹ Underweight: a BMI of less than 18.5.
‹‹ Normal weight: 18.5 to 24.9.
‹‹ Overweight: 25 to 29.
‹‹ Obese: more than 30.

„„

Research has consistently shown a positive association between a
high BMI and greater risk of cardiovascular, pulmonary, and metabolic

11

Changing Body Composition through Diet and Exercise

disease. If you are curious about your own body mass index, calculate it
or look online for a free website that can give you the information.
„„

The problem is that BMI only considers your body weight and body
height and does not account for the proportion of muscle mass or fat
mass—which is the composition of your body weight.

„„

For example, a typical NFL running back is very strong, has lots of lean
muscle mass, and has very little body fat. Assuming that this running
back is about 6 feet tall and a little more than 230 pounds (due to all
of the muscle mass), his BMI would be more than 31 kg/m2. According
to BMI standards, this professional, healthy, lean athlete would be
considered obese, even though common sense tells us otherwise.

„„

Body composition is different from body weight and body mass index.
Body composition is the relationship between the different types of
tissue that comprise your body—in other words, how much muscle and
how much fat make up your body weight.

„„

To account for fat-free mass and not just total body weight, the fat-free
mass index (FFMI) was developed. It is similar to the BMI, but it takes
your fat-free mass, or muscle mass (again, in kilograms), divided by your
height (in meters squared).

„„

This index can quantify your body composition more accurately when
you know that you have extra weight that is mostly muscle. It is not
always a better index, but it is a different index, and like any index will be
more or less useful depending on the specific need for the information.

„„

While the FFMI is not used nearly as much as the BMI, a few research
papers have attempted to come up with normal FFMI values for men
and women. A paper from 2002 in the International Journal of Obesity
and Related Metabolic Disorders found that the average FFMI for young
women is about 15 kg/m2 and for young men is 19 kg/m2. These values
change slightly after age 35, showing that fat mass is gained as we age,
most likely due to a more sedentary lifestyle.

12

Lecture 2—A Healthier Way to Measure Body Composition

„„

„„

These indices are important
to
consider
because
they can be helpful for
knowing
your
health
status and risk for certain
kinds of disease, such as
cardiovascular
disease,
pulmonary disease, and
metabolic disease. It is
well established that if you
have a lot of fat deposition,
particularly around your
waist and belly (near your
major organs), your chance
of developing these types
of
diseases
increases
dramatically.
In addition, knowing your
current body composition
gives you greater clarity
about your starting point
for an upcoming weight
loss intervention. You will
better be able to track your
body’s changes over time
and have a bigger picture
of “success.”

MYTH

Muscle Weighs More Than Fat
This myth is just like saying that one
pound of bricks weighs more than
one pound of feathers: Of course, if
you have one pound of each, then
they both weigh one pound.
But here is the difference: Muscle has
more density than fat. This is a key to
understanding why two people can
weigh exactly the same at the same
height but look entirely different.
If you look at five pounds of fat and
five pounds of muscle, they weigh
exactly the same, but the amount
of muscle is smaller than the same
amount of fat. The muscle is about
a third to a half smaller than the fat
because of its increased density.
When you add muscle, you might
weigh the same, but you could be an
entirely different shape.

Body Fat and Muscle Mass
„„

In terms of body composition, your total body fat includes both essential
body fat and storage body fat. Essential fat includes fat in your organs,
such as the heart, liver, kidneys, intestines, muscles, and bone marrow.
This type of fat is required for normal physiological functioning and
differs greatly between men and women. In fact, it accounts for most of
13

Changing Body Composition through Diet and Exercise

the major body fat differences between genders. Women have about 12
percent essential fat, while men have about 3 percent essential fat.
„„

Women have more essential fat mostly because of its biological function
for reproduction. Women need extra fat stores during pregnancy.
Regardless of whether a woman ever has children or not, she will most
often have slightly more fat than a man.

„„

There is another type of fat that is also required for normal body function.
It is called storage fat, which is fat stored until it can be used for energy
when needed. It includes the visceral fat, or deep fat, around your organs
and the fat just underneath your skin, which is called subcutaneous fat.

„„

Storage fat can insulate your body, helps to maintain your body
temperature, and provides vital protection for your organs. The amount
of storage fat is more similar between men and women—usually just 2
to 3 percent higher in women.

„„

Health issues arise when storage fat becomes excessive. Body fat is
important for supporting daily function and health, but excess amounts
will contribute to overweight and overfat conditions.

„„

The other component of body mass that is not comprised of fat is
called fat-free mass or lean body mass. These terms are often used
interchangeably; however, they are technically different. Fat-free mass is
only the muscle mass that you have, while lean body mass also includes
your muscle mass, bone mass, connective tissue (such as ligaments and
tendons), internal organs, and any essential fat stored in these tissues.

„„

In practice, body composition is often described as a two-compartment
model: fat mass and fat-free mass (or lean body mass). And if you
know these values, it can help you avoid getting stuck in the rut of only
measuring and talking about body weight. It will also give you much
more information about your overall health.

14

Lecture 2—A Healthier Way to Measure Body Composition

„„

Typically, body fat levels are broken into “optimal health” and “optimal
fitness.” These terms are very similar, but in general, “health” refers to
the optimal level for reduced risk of disease, and “fitness” takes a step
further to the optimal level for physical fitness. We should all strive for at
least optimal health, and then optimal fitness.

„„

For women, optimal health is a body fat range of 18 to 30 percent and
optimal fitness is 16 to 25 percent. For men, optimal health is 10 to
25 percent and optimal fitness is 12 to 18 percent. Consider your own
goals to determine which range you should fall into. Then, the next step
is to determine your current body composition.

Measuring Body Composition
„„

Many methods of assessing body composition exist, including direct and
indirect measurements. Direct measurements include dissolution of the
body and physical dissection. This means that to truly know your body
composition, you will have to wait until after you have passed away and
donate your body to science. This is obviously not a viable option.
15

Changing Body Composition through Diet and Exercise

„„

Luckily for us, multiple indirect methods are available to assess body
composition and are fairly easy to get access to. But because each
method is indirect, each will have its own inherent error threshold based
on the accuracy compared to the direct method. That error threshold is
usually somewhere between one and four percent.

„„

Depending on the modality, if you are measured at 30 percent body fat
with a method that has an error threshold of plus or minus 4 percent,
your “true body fat” could really be anywhere between 26 and 34
percent body fat.

„„

While this is somewhat disappointing, these assessment tools are great
for tracking changes over time, as long as the same machine and same
technician is doing the measuring. The skill of the technician can also
make big differences in the measurement that is made in some instances.

„„

Some of the more expensive and laboratory-based methods include the
following.
‹‹ Dual-energy X-ray absorptiometry (DEXA)
‹‹ Hydrostatic, or underwater, weighing
‹‹ Air-displacement plethysmography, or what is commonly known as
the “bod pod”
‹‹ Skinfold measurements using skinfold pinches
‹‹ Bioelectrical impedance analysis using an electrical current
‹‹ Advanced clinical methods, such as computerized tomography (CT)
or magnetic resonance imaging (MRI)

„„

With each technique, we are able to assess body density through your
body volume in water (such as with underwater weighing) or in air (such
as with the bod pod), or via some sort of imaging technique, such as
DEXA, CT, or MRI.

„„

For most of these tests, you can either ask your local gym personnel to
administer them or search for a human performance or exercise science
laboratory at a local college or university.

16

Lecture 2—A Healthier Way to Measure Body Composition

Body Shape
„„

All of these methods can only estimate your relative fat and lean
components. But just how much body fat you have is not the whole
picture. It turns out that where you store that fat may be more important
than how much fat you have.

„„

Typically, fat is stored either around your abdomen in the typical
“apple shape,” called android fat, or around your hips and buttocks
in the typical “pear shape,” called gynoid fat. Depending on where
you store your fat, you can often predict your risk of future health
complications.

„„

The android pattern of body fat indicates a lot of fat stored around your
organs, which is called visceral fat, in addition to fat also underneath
your skin, which is called subcutaneous fat. This fat distribution is much

17

Changing Body Composition through Diet and Exercise

more common in men and is associated with more disease risk than the
gynoid fat distributions.
„„

The gynoid fat deposition is typically thought of as the female pattern
of weight gain. This might actually be protective against disease for
women. However, after menopause, when estrogen production tapers
off, women tend to shift more toward the android obesity that is
associated with men.

„„

A measurement called waist-to-hip ratio, or waist and hip circumference,
was developed to quickly and easily allow physicians to crudely
estimate body composition as well as determine risk based on where
fat is located. The size of your waist (smallest part of your abdomen) in
relation to your hips (greatest protrusion of the buttocks) can quickly
paint the picture of your fat distribution.

„„

There is a standardized set of values that can identify your risk based
on both measurements. For example, your disease risk increases with a
total waist circumference measurement of more than 35 inches (88.9 cm)
for women and more than 40 inches (101.6 cm) for men. And this is for
just for your waist, regardless of hip circumference.

„„

Similarly, a waist-to-hip ratio of greater than 0.86 for women or greater
than 0.95 for men indicates an increased risk for disease. The closer
to 1 or above, meaning a bigger belly than buttocks, gives you the
apple shape. In both cases, improvements in body composition are
recommended to avoid these associated health problems.

„„

Another way that body shape is often described is according to
somatotype, or physique shape. The three clearly defined shapes
include ectomorphs, who are naturally thin with longer limbs and small
joints; mesomorphs, who are naturally muscular with broad shoulders
and narrow waists; and endomorphs, who are more round and soft with
thicker joints.

18

Lecture 2—A Healthier Way to Measure Body Composition

„„

Most people can identify with one of the categories even if they are a
hybrid of two groups. Just keep in mind that the type of body shape
you might naturally be might be hidden or morphed by years of beating
up your body with excess food or, on the other hand, lots of dedicated
exercise to change your body composition.

„„

Regardless, these body shapes are correlated with certain levels of fat
mass and muscle mass. Knowing which category you fall into can also
help you set realistic goals for body composition and performance.

Try This
Find your starting point and work with a fitness professional to have
your body fat percent measured.

Questions to Consider
1. Why should you care more about body composition than body
weight?
2. Why might lifting weights change your waist size but not your
body weight?

19

Lecture 3

How Food Is Digested and Absorbed

E

very bit of the food you eat has a dramatic impact on your body
composition, health, and how you feel. The bulk of this lecture will
focus on the details of digestion and absorption. It will also touch on
how the aging process can interfere with normal digestion absorption—
and how that can affect body composition. You’ll also learn about nutrient
partitioning, which is the manipulation of both nutrient content and nutrient
timing of your diet for specific physiological reasons.

Digestion and Absorption
„„

How does the food you eat enter into your body for storage as glycogen
(stored carbohydrate), fat, or protein? Many processes must happen
inside your body to prepare food for use or storage.

„„

Before the food you eat can be used for energy, it needs to be broken
down inside the body into individual nutrients. This is digestion. Following
digestion, the body must take up, or absorb, the individual nutrients to
either use them or store them for later. This is called absorption.

„„

Foods and beverages provide your body with nutrients that it needs
to sustain itself. The nutrients for our body are split into two main
categories: macronutrients and micronutrients.

„„

Macronutrients, consisting of carbohydrates, fats, and proteins, are used
by your body’s cells to create energy. Micronutrients—vitamins, minerals,
and water—do not provide calories, or energy, but they are required
for many physiological processes in the body, including digestion and
absorption.

20

Lecture 3—How Food Is Digested and Absorbed

„„

Once you take a bite of food, the first section of the gastrointestinal (GI)
tract that it hits is the mouth. The food then travels down the esophagus
and enters the stomach to be chemically and mechanically broken down
into smaller fragments.

„„

After the stomach, these food fragments enter the small intestine,
followed by the large intestine. Whatever nutrients and materials the
body does not use up until this point are excreted through the rectum
and anal canal.

„„

Along the route, your pancreas, gallbladder, and liver all help digest and
absorb the food by producing various enzymes (specialty proteins that
help reactions occur) and enzyme solutions that help break down and
transport foods.

„„

Almost all nutrients within the food you eat must be digested before
they are absorbed. Various physical and chemical activities from the
mouth, stomach, pancreas, and small intestine are responsible for
digestion.

„„

Once all of the nutrients are broken down into their simplest forms,
they are then taken up into the cells of the GI tract to be transported
throughout the entire body. This process is known as absorption.

„„

Most of the carbohydrates, fats, and proteins that you consume are
generally absorbed within 30 minutes after reaching the small intestines.
Any intestinal material that is not absorbed by the time it reaches the
end of the last portion of the small intestine passes through something
called the ileocecal valve and then into the large intestine.

„„

Overall, it can take anywhere from 12 to 70 hours for food remnants to
pass all the way through the colon, and waste products are eventually
excreted as fecal matter through the anal canal.

„„

Your body composition overall is highly influenced by the digestion and
absorption of nutrients from the food you eat.
21

Changing Body Composition through Diet and Exercise

Carbohydrates
„„

Through digestion, more complex carbohydrates are eventually broken
down into individual units, known as monosaccharides. The three
monosaccharides are glucose, galactose, and fructose, with the most
common being glucose.

„„

Most nutrients are absorbed somewhere along the length of the
small intestine, through the brush border—where all of the intestinal
digestive enzymes are produced and stored—into the intestinal cells.
Carbohydrates are absorbed very efficiently and are usually cleared out
of the small intestine more quickly than fats or proteins.

„„

Glucose is absorbed into the intestinal cells by a protein complex called
the sodium-glucose transporter. This is an “active” process, meaning that
energy, or adenosine triphosphate (ATP), is required to make this happen.

„„

After glucose is absorbed into the intestinal cell, it is then transported
out of the cell and into the bloodstream. Some of the glucose simply
diffuses into the blood, but a carrier protein transports much of the
glucose from the intestinal cell into the blood.

22

Lecture 3—How Food Is Digested and Absorbed

„„

Once glucose enters the blood, it goes directly to the liver. This is called
portal circulation. The liver is the main site of glucose metabolism, so it
gets first choice on what to do with the incoming glucose: use it, store
it, or let it move on.

„„

Any glucose that is not metabolized and used in the liver passes through to
systemic, or whole-body, circulation. From here, glucose travels to various
other tissues, where it can be taken up through a facilitated transport
process, using other transport proteins before it is used within that tissue.

Fat
„„

Digestion of fat begins in the mouth by the action of an enzyme called
lingual lipase. Only very small amounts are broken down in the stomach.
The bulk of triglyceride (or fat) digestion occurs in the small intestine.

„„

Before fats are broken into their component parts, they must first
be emulsified by bile. Bile is produced in the liver but stored in the
gallbladder.

„„

Once fat is present in the small intestine, a hormone called
cholecystokinin (CCK) is secreted, and then bile is released through the
bile ducts into the small intestine, and the emulsification process begins.

„„

Once emulsified, pancreatic lipase acts on the fats and further breaks
them into smaller units that can be absorbed and transported for use.

„„

Unlike carbohydrates, fats are a little tricky when it comes to their
absorption and transportation. They are naturally insoluble in water.
Because of this, they cannot move through the brush border or the
blood as individual lipid units.

„„

To solve this problem, broken-down fat particles mix with bile salts and
form a water-soluble substance called a micelle, which then interacts
at the brush border of the small intestine. Fat particles move out of

23

Changing Body Composition through Diet and Exercise

the micelle and into the intestinal cell, and the water-soluble bile salts
continue down through the small intestine until they are reabsorbed and
sent back to the liver.
„„

After the broken-down fat particles—which include free fatty acids,
monoglycerides, and some cholesterol and phospholipid particles—are
in the intestinal cell, they actually combine back together to their larger
original triglyceride form. Then, they are transported.

„„

Fats are not only broken down differently than carbohydrates; they also
travel differently. Fats must travel through the lymph system instead of
the blood. The lymphatic system is a network of vessels that transports
nutrients to the cells and collects cell waste products.

„„

In a slow process, fats move out into the lymphatic vessels and eventually
into the blood, where they freely travel to tissues to deliver the fats for
use or storage. Some fat will be used by your muscle cells to produce
energy, and some will be deposited into your fat cells.

„„

There are many things that affect how fats are used and stored,
including when you last ate, what your overall calorie intake for the day
and exercise habits are, and how physically fit you are.

„„

Because the transportation process for fats is relatively slow, it could
take anywhere from 30 minutes to 3 hours after you eat a high-fat meal
for your blood lipids to reach the highest level. About 5 to 6 hours after
the meal, however, the fats will have been delivered to the designated
tissues, and your blood levels should return to normal.

Protein
„„

24

The structure of protein is very complex. The reason that digestion of
protein makes more demands on the body’s metabolism is because of
the complexity of protein.

Lecture 3—How Food Is Digested and Absorbed

„„

Proteins stay fully intact until they get to your stomach. Large proteins are
broken down into individual amino acids in the stomach by very acidic
stomach juice. Proteins that are still intact after leaving the stomach are
broken down further in the top portion of the small intestine. The end
products of protein digestion are free amino acids, which are absorbed
into the intestinal cell.

„„

Proteins are absorbed in a process more similar to carbohydrates than
fats. This process occurs along the entire small intestine.

„„

Amino acids, just like glucose, require a sodium-dependent carrier to
get into the intestinal cells. There are several uses for particular amino
acids within the intestinal cell. However, amino acids that are not used
within the intestinal cells themselves are transported out of the cells into
the blood and make their first stop at the liver.

„„

About 50 to 65 percent of all ingested amino acids are metabolized in
the liver. The rest of the amino acids are used in other tissues, particularly
the skeletal muscles, kidneys, and brain.

Micronutrients
„„

Macronutrients provide the body with energy. Micronutrients, on the
other hand, do not provide energy. Despite this, micronutrients are vital
to make all of the digestive processes occur, along with hundreds of
other reactions and processes within the body.

„„

Water-soluble vitamins—vitamin C and all B-complex vitamins—are
absorbed into and transported through the blood. With the exception
of vitamin B12, water-soluble vitamins are not stored in the body for long
periods of time. They are either used fairly quickly in the body or are
excreted in the urine, so we need to get them daily from the food we eat.

„„

Fat-soluble vitamins—vitamins A, D, E, and K—are absorbed and
transported much like fats. Unlike water-soluble vitamins, excess fatsoluble vitamins can be stored in the body for a decent amount of time.
25

Changing Body Composition through Diet and Exercise

For this reason, fat-soluble vitamins deficiencies are much less common
than water-soluble vitamin deficiencies.

Anorexia of Aging
„„

For the most part, the GI tract of a healthy individual works like a welloiled machine. Along with the digestive system itself, the endocrine and
nervous systems play a major role in regulating digestion, absorption,
and transportation of nutrients.

„„

Unfortunately, as people start to age, some functions of these
systems begin to slow down. The main cause for these changes is the
degeneration of the enteric nervous system, which is the nervous system
of the GI tract. This can lead to serious GI complications.

„„

Along with biological and nervous system complications, elderly
individuals might experience what has come to be known as “anorexia
of aging.” This refers to a physiological age-related reduction in
appetite and energy intake, which leads to significant weight loss and
muscle wasting.

„„

Basically, as you age, there might come a time when you just don’t feel
hungry very often. While this might lead to weight loss, this is not a
good thing; oftentimes muscle mass is lost, too. Ultimately, low muscle
mass prevents mobility.

„„

Your best bet to avoid or slow this age-related reduction in appetite
is to simply make sure that you are leading a healthy lifestyle. See
your doctor regularly, exercise, and nourish yourself with foods that
contribute to your health.

Nutrient Partitioning
„„

26

Nutrient partitioning is the term used to describe how the food you eat
is stored or partitioned into a specific storage area, such as muscle or
fat. At the most basic level, the more of one type of food you eat—

Lecture 3—How Food Is Digested and Absorbed

carbohydrates, fats, or protein—the more of that fuel you will burn for
energy.
„„

Exercise is the most important and powerful tool to help you use the
foods you eat to improve body composition. If you are active, you will
tend to use the foods you eat to power exercise. But if you are sedentary,
your body will tend to partition the foods you eat to being stored as fat,
instead of being used and stored for a healthy purpose.

Try This
Pay attention to the foods you eat and how they make you feel and
perform.

Questions to Consider
1. Why is nutrient digestion and absorption important to body
composition?
2. What is the biggest determinant of nutrient partitioning?

27

Lecture 4

Nutritional Needs and Cellular Function

I

t is very easy to associate the food you eat with external, appearancedriven end points like body weight. But it’s important to understand
how the food you eat affects you on the inside, because your internal
functioning directly influences how you feel, how you look, and your overall
health. The nutrients you eat are an ingrained part of every cell and tissue
that makes you what you are and who you are. In this lecture, you will
learn which nutrients are needed to keep your cells healthy and what these
nutrients actually do inside your body.

Cells in the Human Body
„„

The cell is the smallest structural and functional unit of any organism. It
is what every living being is made out of.

„„

Our cells vary immensely in size, function, and chemical makeup. Each
cell is a minute version of a human life. Each cell in our body must move,
grow, consume food, excrete waste products, react to the environment
it lives in, and reproduce.

„„

Cells in the human body are constantly communicating to make the
entire organism function. They communicate in response to your
environment, what you touch, and how you move.

„„

Cells bond together to make tissues; tissues make up our organs;
our organs make up all of our organ systems; and our organ systems
combine to make up the organism, which, in this case, is our body.

„„

If your cells are not healthy, then they will not work properly. If the cells
don’t work properly, then the tissues won’t work properly. If tissues
aren’t working, then the systems will begin to fail. Eventually, you will

28

Lecture 4—Nutritional Needs and Cellular Function

most likely experience increased fatigue, decreased physical capacity,
improper nutrient use, and partitioning, which might ultimately lead to
poor body composition as well as serious health consequences.
„„

By keeping your cells healthy and fed with the proper nutrients, you are
keeping your whole self healthy.

„„

The average adult human body is made up of about 30 trillion cells.
When the old cells become damaged, new ones are made to replace
them. The nutrients we get from our food are used to make these new
cells. This is the main reason why nutrition plays such a major role in
cellular health and, therefore, in overall optimal functioning.

„„

Also, certain nutrients from the food we eat can protect cells from early
damage and provide the cells with the fuel needed to produce energy
for our bodies.

Cell Components
„„

The outermost component of the cell is the cell membrane. It is the
boundary that separates the internal components of the cell from the
outside environment. It keeps all of the cellular contents safe so that
they can function properly without being damaged.

„„

The cell membrane is referred to as “semipermeable,” meaning that
it has the ability to filter out important nutrients from damaging waste
products. The membrane allows various nutrients to pass through
the wall and sends the wastes out to be removed from the body. The
permeability of this membrane also allows the cells to communicate
clearly with one another.

„„

All of the dietary macronutrients—carbohydrates, fats, and proteins—
are found in the cell membrane. The most abundant form of fat found
in the cell membrane is the phospholipids, which have a hydrophobic,
or water-fearing, tail and a hydrophilic, or water-loving, head. This love-

29

Changing Body Composition through Diet and Exercise

hate relationship with water is what gives the membrane its unique
structure and stability.
„„

Another type of fat-related compound found in the cell membrane is
cholesterol. The cholesterol improves the mechanical stability of the
membrane and helps regulate the fluidity.

„„

The second major nutrient found in the cell membrane is protein.
Proteins play a small role in forming the structure of the membrane, but
they mostly contribute to the membrane functions. They direct proper
operation within each individual cell and also the healthy functioning of
your entire body.

„„

Lastly, carbohydrates are also found in the cell membrane, but in smaller
amounts compared to fats and proteins. Carbohydrates contribute to
membrane structure and are present in the form of glycoproteins and
glycolipids, which are protein and lipid molecules that have a glucose
or sugar residue attached. These molecules also typically function to
support cellular signaling.

„„

The next important cellular structure that is essentially built from our
foods is the nucleus. The nucleus is the largest organelle, or specialized
structure, within the cell, and it contains the cell’s DNA.

„„

The nuclear envelope surrounds the nucleus. This two-layer membrane
is composed primarily of lipids and proteins. It also contains minerals
that are needed for activities within the nucleus.

„„

The nucleus can be referred to as your “genetic storehouse” because
it contains all of your personal information within its nuclear membrane
walls in the DNA.

„„

DNA is the blueprint for every one of the body’s proteins. The proteins
that make up your tissues, organs, chemical messengers, and more
originate from the coding of DNA and the quality of food that we eat.

30

Lecture 4—Nutritional Needs and Cellular Function

„„

For this reason, it is vital that the nucleus has a solid structure to keep
the DNA safe from damage that occurs from normal metabolic and
oxidative stresses and aging. Nutrition also plays an important role in
protecting your DNA.

„„

Another cellular structure is the mitochondria. Known as the
“powerhouse” of the cell, the mitochondria are responsible for energy
production. All of the nutrients from your food are turned into energy
within the microscopic mitochondria of your cells.

„„

Just like the cell membrane and nuclear membrane, the mitochondrial
membrane is made up of fats and proteins. The mitochondrial membrane
has an inner and outer membrane, both of which play important roles
in energy processes. The mitochondria also use many micronutrients to
assist with producing energy.

„„

The structural and functional integrity of the mitochondrial membrane
is critical to your health. If the mitochondria structure and/or function is
compromised, energy production from that cell will be compromised.
This mitochondrial dysfunction can contribute to several chronic
diseases, including diabetes, heart disease, and Parkinson’s disease.

Omegas
„„

Unsaturated fats are necessary for strong cell membranes. The
membrane is semipermeable thanks to the fluid structure of the fats.
However, saturated and trans fats are much more rigid than unsaturated
fats. They don’t function the same way as the unsaturated fats, and
they cause membranes to be much more rigid than what is optimal,
potentially limiting the functionality of cells.

„„

Diets that are too high in one type of fat—for example, trans fats—
might lead to rigid and brittle cell membranes that cannot communicate
as well as if they were composed of a better mix of fat types. In general,
diets high in unsaturated fats will promote healthy cell membranes.

31

Changing Body Composition through Diet and Exercise

„„

Two categories of unsaturated fats to take particular note of are omega-6
fatty acids and omega-3 fatty acids.

„„

Omega-6 fatty acids are highly concentrated in walnuts, almonds, and
various types of vegetable oils, including corn, soybean, safflower,
cottonseed, sunflower seed, and peanut oil.

„„

Rich sources of omega-3 fatty acids include fatty fish, such as salmon,
tuna, cod, and trout. Some seeds and nuts also contain omega-3 fatty
acids, such as flaxseed, but to a much lower extent.

32

Lecture 4—Nutritional Needs and Cellular Function

„„

Both omega-6 and omega-3 fatty acids are essential for good health;
however, they both play very different roles. Omega-3 fatty acids have
an anti-inflammatory effect in the body, whereas omega-6 fatty acids
have a pro-inflammatory effect.

„„

While some amount of inflammation can help protect the body from
infection and injury, too much inflammation can lead to heart disease,
metabolic syndrome, diabetes, Alzheimer’s disease, arthritis, and many
different types of cancer. As opposed to omega-6 fatty acids, omega-3
fatty acids are known to lower the risk of these diseases by decreasing
the amount of inflammation within the body.

„„

Other nutrients required to maintain healthy cell membranes include
high-quality proteins, fat-soluble vitamins (vitamins A, D, E, and K),
and vitamin C. Whole grains, vegetables, fruits, and lean poultry and
fish will provide you with all of these nutrients and will keep your cell
membranes in top shape.

„„

Because the cell nucleus and your DNA are also made up of nutrients,
the quality of food you eat can greatly impact their structure and function
as well. Unfortunately, despite the barrier provided by the nucleus, DNA
can be damaged from any excess potentially harmful substances (often
called toxins) circulating around in the body.

„„

Damage to DNA can also occur from reactive oxygen species or
excessive oxidative stress, which can be produced as by-products from
the energy we produce from food or even from excessive exercise.

„„

If reactive oxygen species make their way into the nuclear membrane,
they can potentially alter normal DNA functioning. If this occurs, the
proteins that the particular DNA strand produced will no longer be
available to your body. This will lead to poor functioning in your body
and could lead to various disease states.

33

Changing Body Composition through Diet and Exercise

„„

One way to protect this from happening is by eating quality sources of
polyunsaturated fats. You can focus on getting these fats from sources
like fatty fish, flaxseeds, walnuts, and even soybeans.

„„

Other nutrients that are needed to protect DNA include high-quality
protein, antioxidants, and vitamins. The easiest way to get these
nutrients into your diet is to consume foods like lean meat, eggs, dairy,
colorful vegetables, whole grains, and fruits.

B Vitamins, Iron, Sulfur
„„

The mitochondria can use the nutrients we eat and turn them into
energy for everything we do. However, not all foods are created equal
when it comes to efficiency of energy production.

„„

Most of the energy that the mitochondria produce comes from fats and
glucose (carbohydrate) either stored in your body or from your diet. This
energy ultimately ends up in the form of adenosine triphosphate (ATP).

„„

The process of making ATP from our foods is very complex. The obvious
nutrients that are needed for these processes to occur are the energyyielding macronutrients: carbohydrates, fats, and proteins. However,
essential nutrients that are often overlooked when talking about energy
production are the B vitamins, iron, and sulfur.

„„

The B vitamins work to transfer electrons through the electron transport
chain, which produces a massive amount of ATP in your mitochondria.
Iron and sulfur are important components of the protein structures
within the major energy-producing systems of your cells and are used to
simply transport oxygen around your body.

„„

If iron and sulfur are not available from the diet to the mitochondria,
energy production will suffer. Just as with the cell membranes and
the nuclear membranes, nutritional support for healthy mitochondria
function comes from eating foods with a lot of nutrients that are

34

Lecture 4—Nutritional Needs and Cellular Function

minimally processed. Things like green leafy vegetables, complex
carbohydrates, and lean proteins are a great start.

Exercise Levels
„„

Some factors that have nothing to do with food can also impact our
cellular health and function. For example, excessive exercise can actually
cause some damage. Exercise naturally increases the production of free
radicals, which are molecules that have an unpaired electron in their
outer shell. The missing electron in these molecules causes them to be
unstable and highly reactive.

„„

To regain stability, the free radical molecule works to steal electrons from
healthy cells in your body. When this happens, the free radical leaves a
healthy cell damaged and unable to perform its usual functions.

„„

This free radical damage does not stop with one cell. Once one free
radical attack occurs, it sets off a domino effect. The newly damaged
cells move on to other healthy cells as they attempt to become
neutral again. Excessive free radical damage has been associated with
accelerated aging, cancer, diabetes, and coronary artery disease.

„„

Luckily, our bodies have the ability to fight free radical attacks by forming
three natural antioxidants: glutathione, catalase, and superoxide
dismutase. These substances donate extra electrons to free radicals and
prevent them from damaging healthy cells.

„„

The major problem with exercise occurs when it is too extreme, causing
the production of free radicals to exceed the body’s ability to produce
antioxidants. This does not mean that you should shy away from all
intense exercise, however, because your diet can help ward off this
exercise-induced oxidative stress—a diet that includes lots of fruits and
vegetables that are full of antioxidants.

„„

Being still and sedentary can also have a negative impact on cellular
health and integrity. Sedentary lifestyles are associated with increased
35

Changing Body Composition through Diet and Exercise

cardiovascular disease, atherosclerosis, overweight/obesity, diabetes,
accelerated aging, and more. Oxidative stress plays a major role in
these dysfunctions. Sedentary lifestyles can lead to increased oxidative
stress and vascular dysfunction.
„„

Leading a physically active life (but not excessively active or sedentary)
will help keep our cells healthy, happy, and functioning to the best of
their ability.

Try This
Try eating more omega-3 fatty acids to decrease your ratio of
omega-6 to omega-3 fatty acids.

Questions to Consider
1. What is really meant by “you are what you eat”?
2. Provide an example for where specific foods you eat are used
for your cellular functioning.

36

Lecture 5

Bioenergetics: Converting Food to Energy

I

n this lecture, you will learn how we produce energy from the food we
eat and which food choices might be best based on your activity level.
Knowing how to use your energy systems to your advantage is a huge
asset when wanting to change your body composition. After digesting and
absorbing the food you eat, it is amazing how it is used to provide energy
for everything you want to do, including changing your body composition.

Bioenergetics and Metabolism
„„

Bioenergetics is the process of converting the components of the foods
we eat—such as carbohydrates, fats, and proteins—into a usable form
of energy. Bioenergetics relates directly to your overall metabolism,
which is the sum of all energy transformations that occur in your body.

„„

We produce energy by converting the food we eat into adenosine
triphosphate (ATP), which is often called the “energy currency” of the
body because in a sense we “pay” for all of our biological actions with
ATP.

„„

To release the energy from ATP, it is broken apart in a process called
hydrolysis, using an enzyme called ATPase. ATP is broken apart into
smaller components to produce adenosine diphosphate (ADP), a single
phosphate, and energy.

„„

Food is eaten and eventually converted to energy (ATP), carbon dioxide,
and water. And the ATP is used to produce work for all of your metabolic
needs and daily activities. Heat is also produced in the process of
making energy.

37

Changing Body Composition through Diet and Exercise

„„

Essentially, you simply changed the chemical composition of the food
you eat into other forms of useable energy and heat. This follows the
first law of thermodynamics, which states that energy is neither created
nor destroyed, but only changed in form.

„„

ATP is the stored chemical energy that links the energy-producing and
energy-requiring functions within all cells. This energy fuels all forms of
biological work, such as digestion of food and muscle contractions.

Making and Replacing Stores of ATP
„„

We have three energy systems that make and replace our stores of ATP
for us. In all three systems, a phosphate group is added to an adenosine
diphosphate (ADP) molecule in a process called phosphorylation to
create adenosine triphosphate (ATP). That phosphate is added to
ADP and then stored as ATP until the energy from ATP is needed for
activities, such as exercising.

„„

Each energy system has a specific role and works at the highest rate
based on how hard or intensely you are working. Each system has a
different way of providing ATP, but they are used on a continuum and
overlap quite a bit.

„„

In addition, certain parts of each of the three energy systems can also
work to provide ATP in the other two energy systems. In this way, you get
the most ATP out of whatever you are doing and whatever fuel source—
carbohydrates, fats, or proteins—you are using to provide energy.

„„

By understanding these energy systems, you will gain the ability to
decide what to eat, or what certain nutrients may be best to support
whatever you are doing. This allows you to better understand how to
eat what you can use best for energy production, limit storing excess
body fat, and improve success in fat loss.

„„

The three energy-producing systems are the creatine phosphate system,
the glycolytic system, and the oxidative system. All of these systems are

38

Lecture 5—Bioenergetics: Converting Food to Energy

at work for us to provide energy, but one system is typically used more
than the others during different exercise and rest scenarios.
„„

The creatine phosphate system works hardest for us during maximalintensity exercise. In this system, you will create ATP by first combining a
phosphate with stored creatine, which is a combination of amino acids,
to form creatine phosphate. Then, the enzyme creatine kinase breaks off
the phosphate from creatine phosphate and allows it to combine with
ADP. This forms more ATP and free creatine.

„„

This process is anaerobic, meaning that it occurs without oxygen. This
does not mean that you aren’t taking in oxygen by breathing; it just means
that ATP can be produced without the presence of oxygen in the cells.

„„

The creatine phosphate energy system works quickly but does not last
for long; about 30 seconds is all you’ll get (depending on your fitness
level), but it is the most rapid method to regenerate ATP.

„„

The second energy system is the glycolytic system, also called anaerobic
glycolysis, which relies on carbohydrates as a fuel source to make
energy. The glycolytic system lasts longer than the creatine phosphate
system—but probably not more than about two minutes while you
are working hard. Once again, you produce ATP without the need for
oxygen in your cells.

„„

Glycolysis is the breakdown of carbohydrates or glucose to make ATP.
Glucose is in any type of carbohydrate that you eat or drink, such as a
sports drink or piece of bread. Once the glucose is in your blood, you
need to get it into your cells to break it down to either make ATP or
store it as glycogen for later use.

„„

You can use stored glycogen or the glucose from food that you’ve
recently eaten to make ATP. In both cases, you first need to get the
glucose into your cells. There is an elaborate system of proteins called
GLUT transporters that assist with this. The glycolytic energy system is
one you rely on a lot during any kind of physical activity.
39

Changing Body Composition through Diet and Exercise

„„

The third energy system is the oxidative system, which relies on
carbohydrates, fats, and in some cases protein to provide ATP. The
oxidative system is the long and slow system, which kicks in after about
90 seconds to 2 minutes of activity and can last almost indefinitely—as
long as the intensity of activity is low to moderate. It’s aerobic, unlike the
other two energy systems, so it uses oxygen.

„„

The oxidative system is active for most of your day: while sitting
at a computer, walking around, and even just watching television.
Carbohydrates and fats are the primary fuel sources used to provide
ATP in the oxidative system, but this system can also metabolize some
protein for energy production. This does not typically happen, though,
unless someone has been exercising for a very long time (longer than
two to three hours) or for someone who has not eaten in a long time.

„„

You never only use fat or only use carbohydrates. The reality is that the
fuel used to provide ATP in this energy system is typically a combination
of fuels and not an all-or-none kind of action.

Fitness and the Respiratory Exchange Ratio
„„

The fitter you are, the better you become at using fat as a fuel source.
Also, the fitter you are, the better you are at saving your stored glucose
or glycogen until you really need it—such as when you pick up the
intensity of your exercise. This is just one more reason to consider
adding physical activity into your daily lifestyle: It will impact the fuel
you use all day long.

„„

As you exercise and your training status increases, you can increase the
number of mitochondria that you have in the cells of the muscles at
work. This is called mitochondrial density, and you want it to be high.
The mitochondria are the organelles within your cells that help you
produce large amounts of ATP, so it makes sense that the more exercise
you put into your lifestyle, the better you are at making energy.

40

Lecture 5—Bioenergetics: Converting Food to Energy

„„

Another benefit is that you can increase the number of capillaries,
or small blood vessels, you have to bring blood, oxygen, and other
nutrients to working muscles. This is called capillary density, which you
also want to be high.

„„

Additionally, with exercise training, you actually increase the activity
of enzymes called lipases that increase fat breakdown. Exercise also
increases the hormones that are used to help initiate this breakdown.

„„

By making exercise a part of your life, you increase your body’s ability
to effectively use fuels. You decrease your reliance on carbohydrates
and use more fat for fuel, regardless of what you are doing all day.
This means that at rest and during exercise, you are burning a greater
amount of fat. Over time, this will impact your body composition.

„„

The fat that is used to make ATP can come from stored fat tissue, such
as the fat around your waist and hips, or from dietary fat that you’ve
eaten. You even have fat stored in your muscles to use for energy; this
type of fat is called intramuscular triglyceride (IMTG).

41

Changing Body Composition through Diet and Exercise

„„

Interestingly, you’ll find IMTGs in both very fit people and also outof-shape people. But how these storage depots of fat are utilized
is extremely different between the fit and unfit. For the out-ofshape people, these intramuscular fat stores can do harm and alter
the proper cell signaling that should occur in response to various
hormones. But in physically active people, the intramuscular fats tend
to be used as an energy source, sparing glycogen and increasing fat
use for activity.

„„

So, while both fat and carbohydrates will be used in the oxidative system,
the amount of fat used compared to how much carbohydrate used is
highly dependent on a number of key factors, including when you last
ate, when you last exercised, how fit you are, and what hormones are
circulating in your blood.

„„

The human body is amazing and adjusts to what you eat by burning more
of that type of nutrient. This ability to shift easily from one fuel source to
another based on the circumstance is called metabolic flexibility.

„„

In a lab setting, we can determine which fuel source (fat or
carbohydrate) you are using by measuring the amounts of carbon
dioxide and oxygen in your breath at rest or during exercise. The
ratio of carbon dioxide produced to oxygen consumed is called
the respiratory exchange ratio (RER). When burning 100 percent
fat for fuel, your RER is equal to 0.7, but when burning 100 percent
carbohydrate for energy, your RER is 1.

„„

Basically, the faster and harder you go, the greater percent of
carbohydrate that will be used to make energy, or ATP. But there will
always be a mix of carbohydrates, fats, and some proteins used to
produce ATP. The more metabolically flexible you are, the better you
will be at using all the energy sources at the exact right moment.

42

Lecture 5—Bioenergetics: Converting Food to Energy

Try This
Aim to change your food intake and carbohydrate intake based on
your activity level each day.

Questions to Consider
1. If you like to walk as your primary form of physical activity, what
fuel are you most likely to use to provide energy? What source
of food might you want to consider eating more of? Less of?
2. What activities might the first energy system, the creatine
phosphate system, be used for in your typical daily routine?
3. How will understanding nutrient bioenergetics impact the
choices you will make while trying to improve body composition?

43

Lecture 6

Carbohydrates: Composition, Storage,
and Use

I

n this lecture, you will learn why carbohydrates—fruit, pasta, whole grains,
corn, peas, and breads—don’t have to be scary or off-limits. You will also
learn how carbohydrates impact your body composition and health, why
there might be certain carbohydrates to eat at certain times of the day, and
how exercise fits into the puzzle. In the end, you will have a firm grasp of the
many types of carbohydrates that exist, how and why they might impact your
body composition differently, and when you can eat a high-carbohydrate
meal with less fear of storing it as fat.

Glucose and Ketosis
„„

Glucose is the preferred fuel source by your brain and nervous system,
as opposed to protein or fat. The body needs glucose for some actions,
and it is estimated that we make about 50 grams of glucose per day
in a process called gluconeogenesis. This amount is quite low, and for
people who are physically active and like to exercise, the amount of
carbohydrate needed will likely be more.

„„

The current acceptable macronutrient distribution range from the
Institute of Medicine for carbohydrate is between 45 and 65 percent of
your total calorie intake, with no less than 130 grams of carbohydrate
per day to meet our basic physiological needs. Because 1 gram of
carbohydrate yields 4 calories, you will need roughly 500 calories per
day from carbohydrates just to meet minimal needs.

„„

However, more and more research is showing that we might be able
to consume far less than 130 grams per day as long as dietary fat and
protein are increased in the diet.

44

Lecture 6—Carbohydrates: Composition, Storage, and Use

„„

Fortunately, when you eat very little carbohydrate, you can still function
from the production of ketones, which are simply a by-product of excess
fat breakdown as a result of a low-carbohydrate diet. This excess fat
breakdown is called ketosis.

„„

Recently, ketone use for energy has been the topic of much research
and debate. Some experts support nutritional ketosis for weight loss
and health. Nutritional ketosis is induced when a person is put on a
low-carbohydrate diet to encourage the breakdown of excess fat. Other
experts recommend the traditional model of a higher-carbohydrate,
low-fat diet for weight management and health.

„„

The research is clear that some glucose is required for life, and even more
is likely needed if you decide to become extremely active. However,
most scientists agree that the United States is an “over-carbed” nation.
They recommend that steps be taken to identify which carbohydrates
are best to eat at what times during the day to provide the best health
and performance benefits and to minimize negative changes to body
composition.

„„

How active you are, what size you are, and what your specific goals are
will dictate how much carbohydrate you should have in your diet.

„„

Of the three macronutrients (carbohydrates, fats, and proteins),
carbohydrates are traditionally thought of as the most important fuel for
exercise, particularly during high-intensity exercise.

„„

The carbohydrate foods that we eat can range from quite simple, like
sugar, to more complex forms, like starches and fibers. This ultimately
determines how quickly we digest, absorb, and use them to fuel our
activity or store them as fat in our muscles, liver, or fat tissue.

45

Changing Body Composition through Diet and Exercise

Types of Carbohydrates
„„

We classify carbohydrates by their structure, from simplest to most
complex. These include monosaccharides, disaccharides, oligosaccharides,
and polysaccharides.

„„

In all of these types of carbohydrates, the term “saccharide” means
“sugar.” The prefixes “mono-,” “di-,” “oligo-,” and “poly-” refer to
how many sugars are linked together—1, 2, 3 to 9, and 10 or more,
respectively.

„„

The length of the carbohydrate chain is one factor that determines
the rate of carbohydrate breakdown. The shorter the chain, the faster
this rate becomes. In terms of overall health, you want a slower rate
of breakdown to avoid any large variations in blood sugar and insulin
concentrations. Insulin is one hormone that is responsible for inhibiting
our ability to use fat as a fuel.

„„

Another interesting factor that determines the rate of carbohydrate
breakdown is the shape of the carbohydrate. Starch, which is

46

Lecture 6—Carbohydrates: Composition, Storage, and Use

carbohydrate from plant sources, can have two basic forms: amylose (a
straight, long chain molecule that is digested slowly) and amylopectin
(which is highly branched and rapidly digested). Glycogen is also
highly branched and is the form of carbohydrate that we store in our
bodies.
„„

In the context of body composition, we typically just think about the
carbohydrates we eat as something that either makes us fat or doesn’t.
However, we also have to remember that carbohydrates provide us with
fuel to ultimately produce energy, especially when we try to exercise at
a high intensity.

„„

Another source of carbohydrate that has clear health and body
composition benefits is fiber. Dietary fibers are from plants and are not
digested or absorbed by humans, so having these in your diet will slow
the rate of carbohydrate digestion, which is usually a good thing.

„„

Dietary fibers are found in foods like bananas, oatmeal, beans, whole
grains, and dark leafy greens.

„„

Fiber might help you feel more satiated or full for a longer period of
time, lower your blood cholesterol and fat levels, and improve overall
gut health. That means you might eat less by including fiber in your
meals.

Digestion
„„

The process of carbohydrate breakdown starts in your mouth with an
enzyme called salivary amylase. It breaks the long sugars apart into
smaller units to be absorbed. These small simple carbohydrates move
through the cell lining of the small intestine and into the blood in
capillaries that lead to the portal vein.

„„

The portal vein takes blood to the liver, and the liver takes what glucose
it needs for its own energy requirements and also what it needs to store
as glycogen.
47

Changing Body Composition through Diet and Exercise

„„

The remaining glucose continues to circulate in the blood. No matter
what carbohydrate you eat, ultimately it will be in your blood as glucose
because your body favors glucose for production of energy, or ATP.

„„

The fructose you eat is stored as liver glycogen, and once the liver stores
all the glycogen it needs from fructose, fructose then serves to increase
fat synthesis. Clearly, this might not be the best thing for overall health.

„„

The end result of carbohydrate breakdown is glucose being directed into
circulation and ultimately to the cells that need it throughout your body.

Glycemic Index, Glycemic Load, and Insulin Index
„„

There is a limit to how much glucose the body can use, and when those
uses are met, the body responds by storing the energy in other forms,
such as fat.

„„

The glucose in your blood is used by cells to produce energy, especially
by your nervous system and red blood cells.

„„

Glucose can be stored as glycogen for later use, or the fat cells can
remove glucose from the blood to form glycerol that is needed for
triglyceride, or fat, storage.

„„

Our bodies work best for us when blood glucose remains at a constant
level without large fluctuations throughout the day. To a large extent,
blood glucose levels can determine our mood and energy levels.

„„

When blood sugar is elevated for a prolonged period of time, numerous
detrimental health and body composition outcomes may occur,
particularly for people who are hypo- or hyperglycemic. The good thing
is that we have an index that tells us how quickly a food you eat will raise
your blood glucose levels: the glycemic index.

„„

By knowing the glycemic index of common foods that you eat, you will
have an idea of what your blood glucose response will be after you

48

Lecture 6—Carbohydrates: Composition, Storage, and Use

eat that food. The higher your blood glucose, the higher the hormone
insulin is in your blood.
„„

Insulin is highly involved with the storage of carbohydrates in your cells.
Insulin also blunts fat burning in most cases. It plays a critical role in this
important function of balancing blood glucose levels.

„„

If you have high insulin levels for a prolonged period of time, losing fat
will likely be much more difficult to do. High levels of insulin also might
interfere with your ability to achieve optimal health and performance.

„„

Foods like bread, pastries, and bagels have a high glycemic index and
therefore spike your blood sugar. On the other hand, foods like apples,
cherries, beans, and nuts tend to have a much lower glycemic index.

„„

The glycemic index provides a snapshot of good information but
needs to be balanced with some other basic nutrition principles.
One mechanism that has been developed to overcome some of the
shortcomings of the glycemic index is called the glycemic load.

„„

The glycemic load is the glycemic index of a particular food multiplied
by the actual amount of food that you eat. Similar to a high glycemic
index, a high glycemic load of a carbohydrate food means that your
blood glucose values will increase quickly.

„„

This glucose response is used to predict what should happen to insulin
levels. The problem is that there is not always a direct correlation
between a high glycemic index or a high glycemic load food with a high
insulin response.

„„

For this reason, research from The American Journal of Clinical Nutrition
has provided an insulin index of common foods. So, rather than eating
and measuring how high glucose gets in your blood, we would measure
how high insulin gets in response to specific foods.

49

Changing Body Composition through Diet and Exercise

„„

The glycemic index, glycemic load, and insulin index are useful tools, but
other methods for choosing carbohydrates should also be considered.
Ideally, we need a way to monitor the carbohydrates that we eat so that
they serve the greatest benefit to us while also minimizing any negative
impact to our body composition and health.

Balancing Blood Glucose
„„

Lower-glycemic-index, lower-glycemic-load, and lower-insulin-index
foods have the best potential to improve your body composition, keep
you healthy, and avoid large spikes in blood glucose and insulin.

„„

On the other hand, many prepackaged foods and other refined
carbohydrates will quickly get into your bloodstream and over
time have the greatest chance for causing some negative health
consequences, including insulin resistance, where your body has to
produce more and more insulin just to have the same effect it normally
should have.

„„

So, unprocessed carbohydrates like vegetables, which are high in fiber
and nutrient density, should be the staple of your carbohydrate intake,
compared to overly processed carbohydrates and added sugars. Eating
this way regularly should improve your fiber and micronutrient intake
and increase your feeling of fullness, or satiety, for a longer period of
time after eating.

„„

Another step in keeping blood glucose levels balanced is to exercise. At
the end of exercise, your body is primed to store glucose as glycogen.
Additionally, the exercise has increased your body’s insulin sensitivity,
meaning that you are more responsive to less of this powerful hormone.
Theoretically, then, the best time to consume any carbohydrate-heavy
meals would be after vigorous exercise, because you are metabolically
prepared to handle them best at that point.

50

Lecture 6—Carbohydrates: Composition, Storage, and Use

Try This
Aim to eat your most starchy meal of the day, such as pasta, after
your hardest workouts.

Questions to Consider
1. What sources of carbohydrate in your diet would be best for
optimizing your body composition?
2. How many added sugars do you eat on a typical day?

51

Lecture 7

Fat: Not the Nutritional Bad Guy

T

his lecture focuses on the many different valuable and necessary
physiological roles that fat has in the human body. While fat has been
maligned as the nutrition “bad guy” for a long time, there is new
evidence indicating that eating fat is likely not all that bad for health or body
composition, as long as fat intake is not combined with high sugar/refined
carbohydrate intake; fat is consumed in a more balanced manner between
saturated, monounsaturated, and polyunsaturated fats; and total calorie
intake remains aligned with your nutritional and body composition goals.

What Is Fat?
„„

Just as carbohydrates are composed of monosaccharides linked
together, fats are composed of fatty acids. This is the simplest form of
fat. And fat goes by a few names. You might hear about fat as a lipid or
even a phospholipid. All of these are considered fats, and in general,
they are all composed of carbon, hydrogen, and oxygen atoms, just like
carbohydrates.

„„

However, the carbon chain in fats is much longer than the carbon chain
in a carbohydrate. This longer carbon chain is a unique feature of fats
and plays a pivotal role in energy production. All fats also contain nine
calories per gram, making them the macronutrient that provides more
calories per gram than any carbohydrate or protein, which both provide
only four calories per gram.

„„

Fatty acids are found in the food you eat. There are two types of fatty
acids that you’ve heard of already: saturated fatty acids and unsaturated
fatty acids.

52

Lecture 7—Fat: Not the Nutritional Bad Guy

„„

Fatty acids vary by the length of their carbon-to-carbon chain and the
number of hydrogen atoms that surround the carbon chain. That’s the
definition of saturated or unsaturated fat: They are either saturated with
hydrogens or not.

„„

When fatty acids are joined together, you get a triglyceride. Triglycerides
are lipids with three fatty acids that are attached to a glycerol backbone.
Triglycerides are the major storage form of fat in the body and the major
form of fat in your diet.

„„

On a food label, you will often see saturated and unsaturated fats
highlighted. You might also see monounsaturated, polyunsaturated,
and trans fats listed.

„„

Saturated fats are saturated with hydrogens and have no double bonds
in the carbon chain. These fats—like animal fats in meat and butter—are
usually solid at room temperature.

„„

When saturated fats are the predominant source of fat in the diet or just
eaten in excess, they have been associated with increased blood levels
of total cholesterol. And high cholesterol levels have been correlated in
some research to increased risk of heart disease.

„„

However, new research questions the common recommendation that
we need to lower our saturated fat intake from our diets.

„„

Some experts now suggest that high saturated fat in combination with
high intake of sugar and other processed carbohydrates might be the
real problem for our health and body composition. In fact, saturated
fat might be less of a problem than originally thought, as long as
carbohydrate intake is not excessive and a balanced fat intake is in place.

„„

A balance of fat intake occurs when unsaturated fats are also in your
diet. Unsaturated fats contain one or more double bonds along the
carbon chain, meaning that, unlike saturated fat, they are not completely
saturated with hydrogen molecules.
53

Changing Body Composition through Diet and Exercise

„„

There are two types of unsaturated fats: monounsaturated fats and
polyunsaturated fats. Monounsaturated fats have only one unsaturated
bond (also called a double bond), while polyunsaturated fats have more
than one unsaturated (double) bond.

„„

An easy way to identify an unsaturated fat is that it is typically in
liquid form at room temperature. But if unsaturated fats are chilled or
refrigerated, they will solidify.

„„

Examples of monounsaturated fat include olive oil, canola oil, peanut
oil, and sesame oil. You will also find monounsaturated fats in foods like
avocados, peanut butter, and many nuts and seeds.

„„

The polyunsaturated fats are also known as essential fatty acids, meaning
that they are essential to eat because our bodies cannot make them
naturally. Many foods have a mix of fat types, but some examples of
polyunsaturated fats include soybean oil, canola oil, flax, tofu, soybeans,
and fatty fish like salmon.

54

Lecture 7—Fat: Not the Nutritional Bad Guy

„„

Polyunsaturated fats include both omega-6 and omega-3 fatty acids.
These essential fatty acids are needed for immune function, vision, and
cell membrane integrity, among other things.

Omega-6, Omega-3, and Trans Fat
„„

Omega-6 fatty acids ultimately produce compounds that are involved
with inflammation, blood vessel constriction, and immunity. All of these
functions are important, and it’s critical that they are well controlled.

„„

Because omega-6 fats lead to inflammation when taken at high levels,
they are known as pro-inflammatory agents. Eating too many foods with
omega-6 fatty acids, such as heated vegetable oils and many boxed
and packaged grocery items, can compromise health and optimal body
composition, especially when not balanced with other types of fats, such
as omega-3 fatty acids.

„„

Omega-3 fatty acids are beneficial for health, due to their antiinflammatory effects and effects on decreasing blood clot formation.
Some omega-3 fatty acids keep cells less rigid and more fluid. In doing
so, they promote blood vessel dilation, which lowers blood pressure
and can decrease instances of heart attacks.

„„

Omega-3 fatty acid consumption can also lower blood concentrations of
triglycerides, cut the chances of rheumatoid arthritis, and even reduce
some behavioral disorders. Some data even shows that low omega-3
intake is associated with both poor memory and mood disorders.

„„

Because omega-3 fatty acids essentially have the opposite role of
omega-6 fatty acids, a balanced intake of omega-6 and omega-3 will be
needed for optimal health and physical function.

„„

Americans tend to have very high omega-6 fatty acid consumption in
comparison to omega-3 fatty acids in the diet. This is a problem because
a high ratio is reported to promote things like cardiovascular disease,
cancer, and inflammatory and autoimmune diseases. But a higher intake
55

Changing Body Composition through Diet and Exercise

of omega-3 fatty acids seems to have the opposite effect and reduce the
likelihood of cardiovascular disease, cancer, and inflammatory disorders.
„„

If you can’t lower your omega-6 intake, then be sure to reduce the gap
in the ratio by eating more omega-3 fatty acids. For optimal health,
decrease the amount of omega-6 fats that you eat and increase the
amount of omega-3 fats that you eat.

„„

The other type of fat is trans fat. Trans fats are often in the media,
and legislation in the United States to completely ban trans fats from
restaurants has been a big issue.

„„

Trans fat is made in an industrial manufacturing process that adds
hydrogen to previously liquid vegetable oil, making it a solid at room
temperature. The fat is essentially artificially hydrogenated.

„„

This is done to give foods a longer shelf life and might make certain
foods taste better. Many restaurants will use partially hydrogenated
vegetable oils to deep-fry foods because the oil does not need to be
changed as frequently as other types of oils, resulting in a cost savings.

„„

Many foods contain trans fats, including many baked goods, fried foods,
potato chips, and margarine. A diet high in trans fats might increase
your “bad,” or LDL, cholesterol and decrease your “good,” or HDL,
cholesterol. It might also be associated with your risk of developing
heart disease. But some trans fat occurs naturally in food, so it is not
entirely avoidable.

How Much Fat Should You Eat?
„„

56

Opinions vary when it comes to how much of each type of fat you
should eat. The American Heart Association recommends that, for good
health, the majority of the fats that you eat should be monounsaturated
or polyunsaturated, rather than saturated fats and trans fats.

Lecture 7—Fat: Not the Nutritional Bad Guy

„„

Others recommend eating about one-third of each type of fat—
saturated, monounsaturated, and polyunsaturated fats—that includes a
balance of omega-6 and omega-3 fatty acids.

„„

The 2010 Dietary Guidelines for Americans recommends fat intake
between 20 and 35 percent of your total calorie intake and recommends
that saturated fat make up no more than 10 percent of these calories.
They also recommend replacing “solid fats” with oils when possible and
limiting foods with trans fats or hydrogenated oils as much as possible.
The guidelines also recommend eating less than 300 milligrams of
dietary cholesterol per day.

„„

Fat is the most energy-dense macronutrient that we eat, because one
gram of fat yields nine calories. Many people don’t need to seek out
additional fat to eat when considering total fat eaten per day, because
fat is usually in many of the foods that we eat normally.

„„

However, research is showing that it might be useful to make an
effort to eat more high-quality fats in your diet, such as nuts, seeds,
57

Changing Body Composition through Diet and Exercise

avocados, and fish. These foods provide a nice variety of saturated,
monounsaturated, and polyunsaturated fats. And because fats help you
feel full, these foods can be used to help reduce the total number of
calories that you consume in a day.

Burning Fat
„„

Fat provides the most abundant source of energy that we have. It fuels
your body at rest and during activity that is light to moderate in intensity.
During this type of exercise, a muscle’s main source of fat supply is your
fat (or adipose) tissue.

„„

Muscles can also rely on fat that is stored inside of the muscle called
intramuscular triglycerides (IMTG). The amount of IMTG used during
exercise or activity will vary with fitness level. The more fit you are, the
more fat you use.

„„

This is a great adaptation to exercise. With fat stored in your muscle, it
is already located where it needs to be so that it can be used as energy.
The amount of IMTG will also vary with the intensity and duration of
exercise, where longer and slower activity will rely more on fat use than
short and fast activity.

„„

To use fat as a fuel during exercise, your body needs to be able to break
down stored triglyceride into free fatty acids to make ATP for energy.
The intensity of the exercise will determine if fat will be used during
exercise. The more intense the exercise, the less your body will be able
to utilize the fat stores, and vice versa.

„„

Fat oxidation (or burning) is regulated in part by how much glucose you
have in your blood. So, eating lots of carbohydrates will increase blood
glucose and decrease the breakdown of stored body fat (which is called
lipolysis) and fat’s use (or oxidation) for energy.

„„

But fat oxidation is enhanced by exercise training. This occurs because
exercise training can increase the number of mitochondria you have, as

58

Lecture 7—Fat: Not the Nutritional Bad Guy

well as the capillary density. The increase in mitochondria will help the
body process the fat at a higher volume, and the increase in capillary
density will help increase the blood flow and oxygen delivery to the
exercising muscle, which is required to burn fat.
„„

Another interesting aspect of fat burning is the differences we see
between men and women. Recently, it was reported that fat use relative
to total body muscle mass was higher in women than in men. In general,
women also tend to have a higher fat oxidation than men during
exercise of low to moderate intensity. But women and men alike need to
exercise to use fat and to eat in the best possible way to support fat use
and optimal health.

Try This
Add at least two servings of fatty fish to your diet each week or begin
to use a high-quality fish oil supplement.

Questions to Consider
1. What types of fat do you normally eat? What is in your kitchen
now?
2. Does eating fat make you fat?

59

Lecture 8

Protein’s Critical Role in Body
Composition

E

ating more protein might be the best nutritional strategy to manage
body composition, given its influence on metabolism, satiety, and
even maintenance of muscle mass. And the impact of a high-protein
diet when combined with an exercise program can provide even better
results for improving our metabolism and body composition. In this lecture,
you will learn how protein does all of these positive things in our bodies and
how you can use it to improve your body composition.

Protein and Metabolism
„„

In terms of our body composition, eating protein can help boost your
metabolism. In fact, there are a number of foods and supplements
that are thought to boost your resting metabolic rate. But exercise
and nutrition research suggests that you can do that by including more
protein in your diet and by eating lean protein with every meal—such as
chicken, turkey breast, fish, and lean beef. Plant protein sources—such
as beans, legumes, some grains, and tofu—can be incorporated as well.

„„

This strategy can be controversial, but much of the current research
supports the fact that protein should make up about 20 to 30 percent
of your diet. This is higher than the 10 to 15 percent that has been
traditionally recommended.

„„

This recommendation applies to healthy individuals free from kidney
disease (because protein could be an added stress to someone with
diseased kidneys). Protein is especially important when trying to lose
weight.

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Lecture 8—Protein’s Critical Role in Body Composition

Protein Functions
„„

Similar to carbohydrates and fats, proteins contain carbon, hydrogen,
and oxygen, but proteins also have a nitrogen molecule attached to
their structure. It is this nitrogen found in protein that distinguishes it
from the other macronutrients.

„„

Proteins are composed of amino acids that are linked together by peptide
bonds. Twenty different amino acids exist, and they can all combine in
unique ways to make new and different proteins in our bodies.

„„

But because so many different types of foods can provide you with
protein, how can you tell if a specific protein or protein food is goodquality protein? One way to tell is by knowing the biological value of the
protein. The higher the biological value of a protein, the higher its quality.

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Changing Body Composition through Diet and Exercise

„„

There are two types of proteins: essential and nonessential. They are
either essential to include in our diets because our bodies don’t make
them, or they are nonessential because our bodies make them from
other proteins, so we don’t need to worry about eating them. There are
11 nonessential and 9 essential amino acids.

„„

Essential amino acids are the ones we tend to worry about the most.
When proteins contain all of the essential amino acids, they are called
“complete” proteins and have a high biological value. These proteins
are typically from animal sources and include meat, poultry, fish, eggs,
milk, and cheese.

„„

When food does not have all of the essential amino acids, they are
called “incomplete” proteins and have a low biological value. These are
lower-quality proteins that are missing at least one of the essential amino
acids. A diet made up of incomplete proteins might eventually lead to
protein malnutrition. Examples of incomplete proteins are usually found
in plants, grains, nuts, and vegetables.

„„

Classifying the amino acids like this is probably most important for
people who do not eat animal products. This is because animal meats
contain all of the essential amino acids, but plant products generally do
not. This means that one or more of the amino acids will be missing,