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Chapter 8 – Energy Balance and Body Composition
Learning Objectives
After completing Chapter 8, the student will be able to:
1. List the factors that contribute to the body’s energy budget.
2. Discuss the factors that regulate food intake and satiety.
3. Explain the basal metabolic rate and the factors that affect it.
4. Discuss the role of physical activity in balancing the energy budget.
Assignments and Other Instructional Materials
The following ready-to-use assignments are available in this chapter of the instructor’s manual:
• New! Case study
• Worksheet 8-1: Energy Calculation
1
Other instructional materials in this chapter of the instructor’s manual include:
• Answer key for How To (pp. 250, 253) activities
• Classroom activities
• Worksheet answer keys (as appropriate)
Lecture Presentation Outline
4
“Of special interest to…” symbol key: = Hot Topic = Personal Health
= Health Care Professionals = Science Majors
Key to instructor resource annotations (shown to the right of or below outline topics):
PL = Available on Power Lecture DVD-ROM (ISBN 0538797592)
TRA = Transparency acetates: 12e TRA = 12th edition, 11e TRA = 11th edition, 10e TRA = 10th edition
Introductory/whole chapter resources: PL figure JPEGs; Test Bank; IM WS 8-3, CA 8-1
1
Worksheets 8-1, 8-2, and 8-4 contributed by Daryle Wane.
2
Contributed by Mary A. Wyandt, Ph.D., CHES
3
Contributed by Sharon Rady Rolfes.
4
Contributed by Melissa Langone.
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I. Energy Balance 10e TRA 88
Body weight is stable when energy consumed is equal to energy expended. When a greater amount of energy is
consumed than expended, weight increases. When less energy is consumed than expended, weight decreases.
One pound of body weight is equal to 3,500 kcalories.
A. Food Composition
1. A bomb calorimeter is an instrument that measures the heat energy released when foods are burned.
2. Direct calorimetry measures the heat energy released.
B. Food Intake 10e TRA 89
1. Appetite initiates eating through the sight, smell, thought or taste of food. Hunger is the feeling that
motivates us to eat and is controlled by the hypothalamus.
2. Satiation is the feeling of satisfaction and fullness that causes us to stop eating.
3. Satiety reminds us not to eat again until the body needs food.
III. Energy Out: The kCalories the Body Expends IM WS 8-4
Energy expenditure includes basal metabolic activities, physical activity, thermic effect of food, and adaptive
thermogenesis. These energy requirements differ from person to person and are affected by age, gender,
weight, and height. The intensity and duration of physical activity also make a difference.
A. Components of Energy Expenditure 10e TRA 90
1. Basal Metabolism (basal metabolic rate, BMR)
a. Approximately 2/3 of energy expenditure.
b. Supports the basic processes of life.
c. Resting metabolic rate (RMR) is a measure of energy slightly higher than BMR.
d. Factors affecting BMR
1. Aging slows BMR.
2. Height – the taller, the higher the BMR.
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10. Hormones:
a. Thyroid hormones can increase or decrease BMR.
2. Physical Activity IM WS 8-1
a. Most variable and changeable factor with regard to energy expenditure.
3. Thermic effect of food (TEF) is estimated at 10% of total energy intake and involves digestion and
absorption.
4. Adaptive thermogenesis is the adjustment in energy expenditure related to environmental changes.
B. Estimation of energy requirements is affected by many factors.
1. Men generally have a higher BMR than women.
2. BMR is high in people who are growing.
IV. Body Weight, Body Composition, and Health
Current weight standards use height and weight data and do not take body composition into consideration.
These may be misleading.
A. Defining Healthy Body Weight
1. The Criterion of Fashion 11e TRA 19
2. The Criterion of Health
a. Good health supercedes appearance.
b. Longevity is a criterion.
3. Body mass index (BMI) measures relative weight for height.10e TRA 92; IM WS 8-2, HN 8-2, CI 8.1
a. Underweight is a BMI below 18.5.
B. Body Fat and Its Distribution IM CA 8-2
1. Some People Need Less Body Fat
a. Fat for fuel.
2. Some People Need More Body Fat 10e TRA 93
3. Fat Distribution
a. Visceral fat is found around abdominal organs and may be critical. 11e TRA 20
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c. Subcutaneous fat is found around the hips and thighs (lower body fat).
4. Waist Circumference
5. Other Measures of Body Composition 10e TRA 95
a. Monitoring changes over time is important.
b. Skinfold measures.
C. Health Risks Associated with Body Weight and Body Fat – An appropriate weight for an individual
depends on many factors that include body fat distribution, health history, and current state of health.
10e TRA 96
1. Health Risks of Underweight
a. Cannot handle medical stresses.
2. Health Risks of Overweight IM CI 8.2; Website HN 8-2
a. Diabetes.
b. Hypertension.
3. Cardiovascular disease and obesity have a strong relationship.
4. Diabetes and obesity have a strong relationship.
a. Insulin resistance and obesity have a strong relationship.
5. Inflammation and the Metabolic Syndrome
a. High blood pressure.
6. Cancer risk increases with weight gain but the relationship is unclear.
7. Fit and Fat versus Sedentary and Slim
V. Highlight: Eating Disorders IM CI Highlight
Many individuals, including young females, suffer from eating disorders. These include anorexia nervosa,
bulimia nervosa, and binge-eating disorders. The causes include a combination of sociocultural, psychological,
and perhaps neurochemical factors. Athletes are among the most likely groups to develop eating disorders.
A. The Female Athlete Triad 10e TRA 103
1. Disordered eating habits can develop.
a. Desire to improve performance.
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2. Amenorrhea
a. Characterized by low blood estrogen, infertility, and mineral losses from the bone.
3. Osteoporosis
a. Stress hormones compromise bone health.
B. Other Dangerous Practices of Athletes
1. Food and fluid restrictions to make weight in wrestling.
2. Muscle dysmorphia is a psychiatric disorder concerning obsession with building body mass.
C. Preventing Eating Disorders in Athletes
1. Educate about inappropriate dietary habits.
D. Anorexia Nervosa
1. Characteristics of Anorexia Nervosa
2. Treatment is multidisciplinary.
E. Bulimia Nervosa 10e TRA 104
1. Characteristics of Bulimia Nervosa
2. Treatment of Bulimia Nervosa
a. Weight maintenance.
F. Binge-Eating Disorder is an unspecified eating disorder sharing some of the characteristics of anorexia
nervosa and bulimia nervosa yet does not meet the criteria for diagnosis.
1. Lack of self–control over eating with binges.
2. Consuming large quantities of food, eating quickly, feeling uncomfortably full, eating alone, and
G. Eating Disorders in Society
1. Occur more commonly in developed nations where food and money are plentiful.
2. Learning to appreciate the uniqueness of oneself may be a key to prevention.
Case Study
5
Rick is a healthy 17-year-old high school student who is 5 feet 10 inches tall and weighs 205 pounds. He has
decided to “get a six–pack” over the summer by dieting and beginning an exercise program. As part of his new plan,
he reports he has stopped drinking soda and is eating more salads. Besides these changes, he is unclear on what his
5
Contributed by Barbara Quinn.
1. Using the information in this chapter, calculate Rick’s BMI and determine what weight category he falls in.
2. Based on the “How To” section on page 253, what would be an approximate initial target weight for Rick to
aim for? Explain your answer.
3. Assuming he swims or works out with weights at least 8 hours a week, use the “How To” on page 250 to
calculate Rick’s estimated energy requirements at his current weight of 205 pounds.
4. At his current level of physical activity and estimated energy requirements from question #3, what is a
reasonable daily calorie goal for Rick to lose 1 pound of body fat per week? Explain how you derived this
number.
5. Using information from this chapter and based on his calorie needs for weight loss from the previous question,
how many grams of carbohydrate, protein, and fat Rick should be eating to each day to accomplish a calorie
distribution of 55 percent carbohydrates, 15 percent protein and 30 percent fat?
6. How would you interpret these results into a reasonable eating plan for Rick?
Answer Key:
1. BMI = (205 pounds x 703 ) ÷ 70 inches ÷ 70 inches = 29.4 (high end of overweight category).
Suggested Classroom Activities
This chapter provides an opportunity to discuss concepts regarding body weight and body composition and often
generates student interest and questions. These topics seem to spark much discussion.
Classroom Activity 8-1: Chapter Opening Quiz
Objective: Introduction to chapter Class size: Any
Instructions: As a way of introducing any new chapter, give a quiz to the class. This is a quiz designed to be
projected overhead. For details, please see Chapter 1, Classroom Activity 1–7.
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Classroom Activity 8-3: Body Composition Assessment: Bioelectrical Impedance
6
Key concept: Assessment of body composition Class size: Any
Instructions: In an attempt to demonstrate the difference between body weight and body fat, body composition tools
can be brought into the classroom. If available, obtain a bioelectrical impedance analysis (BIA) tool. This instrument
How To “Try It” Activities Answer Key
How to Estimate Energy Requirements
The student should first determine his/her weight in kg (weight in lb./2.2) and height in m (height in in./39.37) and
select the appropriate EER equation to use: EER = 662 – (9.53 x age) + PA x [(15.91 x wt) + (539.6 x ht)] for males,
How to Determine BMI
The student should plug her/his weight and height into one of the equations provided in the How To box to calculate
BMI, evaluate the BMI based on the categories listed in the chapter, and, if the BMI is outside the healthy range,
determine how much she/he should weigh to have a BMI 2 units closer to the normal range. For example, a person
who is 5’6” and weighs 115 lb. would have a BMI of (115 x 703)/662, or 18.6, which is within the normal range. A
person who is 5’1” and weighs 152 lb. would have a BMI of (152 x 703)/612, or 28.7, would be overweight, and
would need to reduce his/her weight to (26.7 x 612)/703, or 141 lb., achieve a BMI of 26.6.
Critical Thinking Questions
7
These questions will also be posted to the book’s website so that students can complete them online and e–mail their
answers to you.
1. Discuss the differences between direct and indirect calorimetry. Give an example of each and provide
information as to the importance in the difference between the two. Finally, define the thermic effect of food. Is
this related to calorimetry?
Answer: Direct calorimetry is most often performed in a bomb calorimeter, which measures the energy value of
food. Within the bomb calorimeter (which is a sealed and vacuum-closed space), foods are burned to establish
2. What are important factors that the RD would assess in their client with regard to appetite and achievement of
energy balance?
Answer: Hunger: Is the client able to differentiate between hunger and the variety of other reasons why an
individual may eat? People often eat not because they are hungry but because they are stressed, in social
3. You are working with two clients that are anxious to improve their health status through diet and exercise.
Lucy is 5’9” in height and weighs 200 lbs. Lucy is 35 y/o and is active with her family and her job. She tries to
exercise about two times weekly but has a lot of stress in her life with young children and a full time job.
Recently, she has not been feeling well and her whole family has promised to help her with family
responsibilities so that she can take the time to increase her exercise and do what is necessary physically to “feel
better.”
Bob is a 55 y/o who has had a successful career in marketing. At present he weighs 225 lbs. and is 5’11”. He
walks occasionally with his wife and through airports to catch his flights, but otherwise admits he is a “couch
potato.” As of late, his cholesterol is high and his physician is concerned about his cardiovascular health status.
Calculate their BMR as well as their Estimated Energy Requirements. Discuss how you believe that you can
help Lucy and Bob increase their BMR through your recommendations and their actions.
Answer: To calculate the BMR for Lucy and Bob, use the Harris-Benedict equation that is outlined in the text:
For men: (10 x wt. in kilograms) + (6.25 x ht. in centimeters) – (5 x age) + 5 = BMR
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4. Determine your BMI. Is your BMI in a healthy range? If not, why not? Do you believe that measuring body fat
percentage may more accurately reflect your body composition? Briefly discuss each body composition
measure and discuss why measuring body fat is important to assessing a client’s overall health status.
Answer: For each student, the answer will be different with regard to their BMI. Hopefully they will be honest
and realistic about their BMI as the question serves to help them understand a bit more about their own health
status and what, if any, changes they might need to make when entering the health care field. Our clients seek
us out as role models; therefore, students need to know what goals they may have for themselves.
Developing skill in assessment of body fat via the skinfold calipers in crucial in gathering reliable results. Body
fat assessment is determined by three measurements on an individual: back of the arm, stomach, and hip. These
measurements are put into an equation that has been tested for reliability and validity, and estimating total body
fat with the skinfold calipers rated well with good technique.
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calipers, which are on the high end of cost; therefore, while a researcher/clinician may be quite experienced,
inexpensive calipers may similarly affect reliability and validity of the outcome.
To prevent some of this individual and instrument variability, multiple skinfold assessments are recommended.
Some researchers utilize the mean of three measures or take the mean of three different researcher/clinician
assessments.
Using a technique such as bioelectrical impedance allows a researcher/clinician to quickly calculate an
individual’s total body fat without pain, an invasive technique, and lengthy caliper assessments and
calculations.
Subjects/clients do not feel the small electrical current that passes through the body tissues and performing a
bioelectrical impedance (BIA) test is relatively quick (less than five minutes). Electrode placement, while
important, is much easier to establish if the assessor follows the clear diagrams as compared to the skinfold
caliper technique, which requires not only skill in site choices but also in technique of lifting the skinfold for
proper assessment.
Measuring body fat via hydrostatic measurement is based on the premise that when the subject is fully
submerged in a tank of water of a known temperature, and assuming the subject is able to expel all air from
their lungs prior to submerging under water, the difference in the subject’s density from that of the water
density can be measured. Subjects are asked to wear a light bathing suit for the test. Their height and weight is
taken prior to the subject entering the tank. Once the subject enters the hydrostatic tank, she/he is seated on a
swing-like chair and asked to blow all of the air out of her/his lungs prior to bending down into a fetal position
under the water. Once the subject is submerged, it is crucial that they remain still for several seconds while the
researchers record their underwater measurement. Researchers indicate to the subject prior to submersion how
they will notify that the measurement has been taken and it is OK to come to the surface.
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The air-displacement plethysmograph system measures body composition by determining body volume and
body weight. Once those two variables are determined, body density can be computed and inserted into an
equation to provide percent fat measurements. Body weight is easily determined by the use of an accurate scale.
Body volume is determined by applying the gas law (p1V1 = p2V2) and expansion of Boyle’s Law, pV = c. The
air-displacement plethysmograph measures volume by monitoring changes in pressure within a closed chamber.
These pressure changes are achieved by oscillating a speaker mounted between the front testing chamber and a
rear reference chamber, which causes complementary pressure changes in each chamber. The pressure changes
5. Your book points out that “an estimated 300,000 people die yearly from obesity–related diseases.” Outline some
of these obesity-related diseases and what costs might be associated with each disease. What is your role as an
RD in helping to prevent obesity-related diseases overall?
Answer: There are several comorbidities associated with obesity, and the costs associated with obesity and its
comorbidities continues to climb as health care costs continue to spiral out of control. Common diseases
The role of weight gain in cancer development is still being researched; however, we do know that fat tissue is a
source of estrogen, more specifically in women. High estrogen is associated with some cancers, but as your
book indicates, more work is still being performed to understand the exact relationship between obesity and
cancer. One other factor to consider might be the types of diet that lead to weight gain and whether an
individual is sedentary or not. Given the multiplicity of factors that may be a part of this picture, certainly there
is much to study.
6. In this Highlight, the eating disorders anorexia nervosa, bulimia nervosa, and binge-eating disorder are
discussed. As indicated by this Highlight, it should be clear that these are complex disorders and while there are
some basic theories as to the rationale for the behavior, there is still much to learn regarding the etiology,
prevalence, and treatment of eating disorders. Nutrition and nutrition education will be a very important part of
treating a client with an eating disorder. If you were to work on an eating disorder team, what types of skills
might you want to more fully develop and why? What types of additional skills might you want to have? What
value would they bring to you as the nutrition expert, to your client and the team?
Answer: Highlight 8 does a good job of providing an overview of eating disorders, yet the student requires an
understanding of the complexity of these disorders, the resistance of each to treatment, and the need for
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given eating disorders appear to be so resistant to treatment, particularly the more severe the client case. Family
involvement is important but requires skilled practitioners and thoughtful approaches.
Working in teams is not always an easy task and with this particular client population it is essential that the
team work together. Dietitians that are not particularly keen on working in teams should seek an alternative
career route. So too should the RD understand the fatigue that can be involved in working with an eating
disordered client. Much patience is required to work in this client population as well as skill in working with
very emotionally labile individuals. A significant amount of counseling ability is needed to be successful as
well as a strong emotional constitution within the RD.
Nutrition education not only for team members, to communicate what you are doing with clients, but also to the
community and to coaches can be a vital part of helping to prevent eating disorders. However, providing
nutrition education to some segments of society is not always that easy. Some sports, such as ice skating and
gymnastics as well as wrestling, have years of history as to how nutrition programs were handed down to the
athletes. While tradition is changing slowly, within each community change is a process of communication and
trust. Sharing information and working together with the coaches to optimize their “bottom line” may take a
message much farther than trying to change the whole program.
IM Worksheet Answer Key
Worksheet 8-1: Energy Calculation
Worksheet 8-2: Body Mass Index (BMI): Reality vs. Myths
Worksheet 8-3: Chapter 8 Crossword Puzzle
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Worksheet 8-4: Energy In and Energy Out (Internet Exercise)
Canadian Information
8
8.1 Canadian Guidelines for Body Weight Classification in Adults
Health Canada published Canadian Guidelines for Body Weight Classification in Adults in 2003 based on a
technical report developed by Health Canada staff and an Expert Working Group of Canadian researchers and
practitioners.
9
The weight classification system uses two measures—body mass index (BMI) and waist
Table 8.1 – Canadian BMI Categories and Levels of Health Risk
10
BMI Category
(kg/m2)
Classification
Risk of Developing Health
Problems
<18.5
Underweight
Increased risk
18.5 – 24.9
Normal weight
Least risk
25.0 – 29.9
Overweight
Increased risk
High risk
Extremely high risk
The guidelines use waist circumference as an important indicator for increased risk of type 2 diabetes, coronary
heart disease, and hypertension. These waist circumferences are associated with increased risk:
11
• men ≥102 cm (40 in.), and
• women ≥88 cm (35 in.).
8
Contributed by Gail Hammond.
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Table 8.2 – Summary of Health Risk Classification According to BMI and Waist Circumference
BMI
WC
Normal
Overweight
Obese Class I
<102 cm males
<88 cm females
Least risk
Increased risk
High risk
8.2 Distribution of Body Weights in Canadian Adults
Measured height and weight data from the 2004 Canadian Community Health Survey (CCHS) provide data for the
BMI of Canadians.
13
Canada’s Nutrition and Health Atlas provides information for:
• measured body mass index (BMI) of both children and adults (based on 2004 CCHS),
• physical activity levels of Canadians, and
Table 8.3 – Percentage of Canadian Adults in each BMI Category (2005)13
BMI Category
Percentage
Underweight (<18.5)
2%
Normal Weight (18.5 – 24.9)
38.9%
Overweight (25.0 – 29.9)
36.1%
Obese (≥30)
23.1%
Highlight 8: Eating Disorders
The National Eating Disorder Information Centre (NEDIC) provides information and resources on disordered eating
Increased risk
High risk
Very high risk
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Worksheet 8-1: Energy Calculation
Using Table 8-2 in your textbook, calculate the amount of expended kcalories for each of the identified activities.
Show each step of the calculation process.
1. Male client weighing 175 pounds who does weight lifting (vigorous effort) for 15 minutes three times a week.
4. Female client weighing 115 pounds who rides a bicycle (averaging 19 mph) each day for 20 minutes.
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Worksheet 8-2: Body Mass Index (BMI): Reality vs. Myths
Reality
Myth
If your BMI > 25 you are considered to be overweight.
Only a high BMI affects health status.
If your BMI > 30 you are considered to be clinically
obese.
You only have to worry when your BMI > 40 because
only then you are considered to be morbidly obese.
Using the following data, calculate the client’s BMI and determine whether they are considered to be underweight,
healthy, overweight or obese.
1. 5 foot 8 inches, 160 pounds
BMI = _______________; client is considered to be ____________________________.
4. 5 foot 4 inches, 150 pounds
BMI = _______________; client is considered to be ____________________________.
5. 5 foot 10 inches, 240 pounds
BMI = _______________; client is considered to be ____________________________.
considered to be at the right weight for your given
height.
If your BMI < 18.5 you are considered to be
underweight.
Only a low BMI affects health status.
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Worksheet 8-3: Chapter 8 Crossword Puzzle
Across:
Down:
4. excess fat around the trunk of the body
5. the feeling of satisfaction and fullness that food
brings
7. the size of a person’s bones and musculature
1. eating in response to arousal
2. body weight below some standard of acceptable
weight that is usually defined in relation to height
3. the feeling of satisfaction that occurs during a meal
1
3
2
4
5 6
7 8
9
10
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Worksheet 8-4: Energy In and Energy Out (Internet Exercise)
Go to the following website to answer questions 1-5:
answering these questions. You will be directed to click on another link on the page to answer question 6.
1. A female aged 16 who is sedentary should consume 1,000 calories per day.
a. True
b. False
2. Which of the following statements is accurate concerning the estimation of calorie requirements for gender and
age group for the three designated levels of physical activity?
3. To reduce energy in by 150 calories (kcal) for a 150-pound person, one should eat a 6-ounce can of tuna that is
4. Eating 150 extra calories (kcal) per day can lead to a weight gain of 10 pounds in one year’s time.
a. True
b. False
5. To increase energy out by 150 calories (kcal), one can dance for 30 minutes.
6. Click on this link to get to Energy Out Activities:
a. 380 calories
b. 270 calories
c. 360 calories
d. 150 calories
e. 72.5 calories
_____ 15 minutes raking leaves
_____ 45 minutes of swimming laps, medium level
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Handout 8-1: How To Determine Body Weight Based on BMI
A person whose BMI reflects an unacceptable health risk can choose a desired BMI and then calculate an
appropriate body weight. For example, a woman who is 5 feet 5 inches (1.65 meters) tall and weighs 180
pounds (82 kilograms) has a BMI of 30:
BMI = 82 kg = 30
1.65 m2
or
A reasonable target for most overweight people is a BMI 2 units below their current one. To determine a
desired goal weight based on a BMI of 28, for example, the woman could divide the desired BMI by the
factor appropriate for her height from the table below:
To reach a BMI of 28, this woman would need to lose 11 pounds. Such a calculation can help a person to
determine realistic weight goals using health risk as a guide. Alternatively, a person could search the table
on the inside back cover for the weight that corresponds to his or her height and the desired BMI.
Height
Factor
Height
Factor
Height
Factor
4’7” (1.40 m)
0.232
5’3” (1.60 m)
0.177
5’11” (1.80 m)
0.139
4’8” (1.42 m)
0.224
5’4” (1.63 m)
0.172
6’0” (1.83 m)
0.136
4’9” (1.45 m)
0.216
5’5” (1.65 m)
0.166
6’1” (1.85 m)
0.132
4’11” (1.50 m)
0.202
5’7” (1.70 m)
0.157
6’3” (1.90 m)
0.125
5’1” (1.55 m)
0.189
5’9” (1.75 m)
0.148
6’5” (1.96 m)
0.119
5’2” (1.57 m)
0.183
5’10” (1.78 m)
0.143
6’6” (1.98 m)
0.116