340
CHAPTER 14
Eating and Weight
Lecture Outline
I. The Digestive System
The digestive system begins in the mouth, where food is ground into small particles and
mixed with saliva from the salivary glands. After swallowing, peristalsis propels food through
the esophagus and into the stomach, where it is mixed with acidic gastric juices, but most
II. Factors in Weight Maintenance
The weight equation consists of three factors: calories eaten, calories used in basal
metabolism, and calories expended through physical activity. People obtain calories through
eating, which has regulating components in the nervous system. A variety of hormones and
neurotransmitters influence eating, some by prompting eating and others by signaling satiation.
Low levels of the hormone leptin signal low fat stores and prompt eating. Insulin is another
hormone involved in weight regulation; high insulin levels are related to high body fat. The brain
contains receptors for both hormones, especially in the hypothalamus. Other hormones and
peptides are produced in the hypothalamus. The hormone ghrelin may be a short-term hunger
signal, and cholecystokinin is a peptide hormone that affects feelings of satiation.
A. Experimental Starvation
During World War II, Ancel Keys and his associates conducted a now classic study on
experimental starvation. This study indicated that the body slows metabolism to adjust for
caloric restriction. Many of the volunteers in this study had difficulty meeting the goal of
losing 25% of their body weight. As a result of their food restriction, they experienced
irritability, increased aggression, increased apathy, loss of sexual interest, and lethargy.
When the men were permitted to eat as much as they desired, most easily regained their lost
weight, and many remained obsessed with food and regained more weight than they had lost.
B. Experimental Overeating
III. Overeating and Obesity
Eating and Weight
341
Individual variation in body metabolism allows some people to burn calories faster than
others. Thus, overeating and obesity are not perfectly related, but people who are overweight
usually eat more than those who are not.
A. What Is Obesity?
B. Why Are Some People Obese?
Several models have attempted to explain reasons for obesity.
1. The Setpoint Model
2. Genetic Explanations of Obesity
Looking into human prehistory, individuals who had a tendency to put on fat had a
3. The Positive Incentive Model
The positive incentive model assumes that positive reinforcement plays an important
role in weight maintenance. People can have several motives for eating or overeating,
Eating and Weight
C. How Unhealthy Is Obesity?
hips.
IV. Dieting
Increasing weight combined with an idealization of thinness has made dieting a common
pursuit. Dieting is not even restricted to people who are overweight, and significant percentages
of high school girls and boys and adult women and men in the United States are either dieting or
trying not to gain weight. Young people, girls, and women diet more often than those from other
groups, and they do not always choose wise strategies to lose weight.
A. Approaches to Losing Weight
People have many choices of diets, but all diets that work do so through restriction of
calories.
1. Restricting Types of Food
Restricting portion size is a reasonable strategy, but people find this approach
2. Behavior Modification Programs
Because weight loss is not a behavior, behavior modification programs reinforce
3. Exercise
A regular physical activity regimen should be a component of any weight loss
4. Drastic Means of Losing Weight
Use of diet pills, fasting, and surgery are drastic means of losing weight that are
Eating and Weight
343
5. Maintaining Weight Loss
Relapse is a major problem for weight loss programs, and the more successful
programs include some posttreament components to help dieters maintain weight loss.
Some overweight people are successful in losing weight and keeping it off. These dieters
are less likely to use drastic means and more likely to exercise and rely on a variety of
foods, especially fruits, vegetables, and whole-grain cereals. Family-based programs and
residential programs can be effective in changing the eating and activity habits of
overweight children.
B. Is Dieting a Good Choice?
Some experts recommend against dieting and counsel overweight people to stop
overeating, exercise regularly, and maintain their health. Although some people gain health
benefits from dieting, others increase their risks by losing weight. Voluntary weight loss: that
is, weight loss not due to illness, may improve cardiovascular risks but not overall mortality
risk. Thus, dieting may be a good choice for some people but not others.
V. Eating Disorders
Anorexia nervosa and bulimia are two eating disorders that begin as attempts to control
weight. Body dissatisfaction is widespread and an important precursor for these eating disorders.
Binge eating is a third eating disorder and a significant factor in being overweight or obese.
A. Anorexia Nervosa
Anorexia nervosa is an eating disorder characterized by intentional self-starvation or
semistarvation, sometimes to the point of death. In the past, anorexia was regarded as a
“nervous” disorder or as a denial of femininity. However, today most observers view this
eating disorder as a learned syndrome of behaviors.
1. What Is Anorexia?
2. Who Is Anorexic?
3. Treatment for Anorexia
Despite a variety of treatment programs that have been used with anorexics, success
rates are low, but mortality rates are between 5 and 10%. Most anorexics are poorly
motivated to change eating habits, and they resist suggestions that they are too thin. As
starvation continues, and as they reach the point of exhaustion and physical collapse,
some form of medical intervention is usually forced on them. Forced feeding usually
Eating and Weight
restores weight, but it is not a cure. Research suggests that about 75% of anorexics
recover and between 9-18% continue to experience pathology. Cognitive behavioral
programs attack anorexics’ irrational beliefs and build reasonable eating habits. This
effective therapy is underutilized in treating anorexia and may be more effective than
other approaches for the common problem or relapse.
B. Bulimia
People with bulimia eat huge quantities of food in an uncontrolled manner (binge) and
then get rid of the food by vomiting or using laxatives (purge).
1. What Is Bulimia?
2. Who Is Bulimic?
3. Is Bulimia Harmful?
4. Treatment for Bulimia
Unlike anorexics, bulimics are usually motivated to seek help and to get better. The
immediate aim of treatment is a change in eating patterns, but long-term goals usually
that underlies this eating disorder.
C. Binge Eating Disorder
Binge eating disorder consists of the same out of control eating that symptomizes
bulimia, but without purging. This eating pattern will be included as a disorder in the DSM-V
1. Who Are Binge Eaters?
Eating and Weight
345
disorders.
2. Treatment for Binge Eating
Treatment for binge eating faces the challenge of changing a maladaptive eating
pattern and helping individuals lose weight. Programs have been more successful with
the former than with the latter.
Exploring Health on the Web
Information about obesity, weight management, and eating disorders is plentiful on the Internet.
This website is the official website of the National Eating Disorders Association
(NEDA), which is the leading non-profit organization in the United States.
This USDA website focuses on government regulations for food. It also provides
information on how much food is exactly a “cup” of vegetables or fruits.
Eating and Weight
346
This website is part of larger social-change website. It contains many articles and videos
that combine many societal issues—such as food, diversity, and environmental issues in this
Suggested Activities
Personal Health Profile — Understanding Eating Habits
Most of your students are likely to have a personal interest in weight control—a few may
be trying to gain weight, but more will be attempting to lose weight. Many will have some
information about which diet is most effective, and much of that information may come from
secondary sources such as textbooks, newspapers, and magazines, or from advertisements
designed to make a profit by influencing people to buy a particular commercial product. In this
chapter (as in the previous two), students should construct their Personal Health Profile based on
an evaluation of research rather than social or media sources. Therefore, your students should
once again critically analyze the evidence on diet and eating patterns.
weight loss.
Instruct students to keep a diet diary so that they can understand their eating habits. Urge
them to keep an accurate account of what, when, where, and how much they eat without making
changes in their eating. This record will allow students to evaluate their eating for nutrition and
understand how wise their diet choices are. For those who are trying to lose weight, are they
doing so for health or fashion reasons? Is dieting a cyclic pattern of losing and gaining? Are any
of their diet practices more dangerous than remaining at their prediet weight? Do they skip meals
out of a desire to lose weight or because of time constraints? Does their eating reveal any
symptoms of disordered eating?
Debate: Is Losing Weight Beneficial or Risky to Health?
Losing weight has both potential benefits and risks, which vary depending on the person
who is dieting and the method used to lose weight. These possibilities offer the format for a class
debate about dieting. The debate is on the topic of whether or not weight loss is more of a health
benefit than a health risk. (Make sure that your debate centers around the health benefits and
health risks of weight loss and not on the advantages of wearing a size 2.)
The Media‘s Role in Body Image and Eating Disorders
The media have been accused of promoting a thin ideal body image that has increased the
prevalence of eating disorders. Guide your students to examine print and electronic media for
Eating and Weight
347
examples of idealizing bodies that are too thin to be healthy. Lead your students to pay close
attention to gender in their examination, looking for how women’s bodies are held to a different
standard of thinness than men’s bodies. Do men escape body image dissatisfaction, and if not,
how do the media contribute to their body dissatisfaction?
An extension of this activity involves examining the proanorexia websites on the Internet.
Using the label pro ana, these websites offer support, advice, and encouragement to those who
wish to remain anorexic. Some search engines have attempted to control these websites by
restricting them from their searches, but search terms such as pro ana, pro ana nation, and
thinspiration will allow your students to examine the thoughts and feelings of those with
anorexia nervosa and to begin to grasp how difficult it can be to get these individuals to accept
treatment.
Cognitive Distortions and Anorexia
Healthy Eating at School
If your school is typical, about 70 percent of the women and 20 percent of the men on
campus would like to lose weight. Have your students determine how easily a student can eat a
healthy diet to lose weight at the school cafeteria by estimating the caloric content, fat grams, or
both of food served in the cafeteria.
Students who work on this activity should be as accurate as possible in estimating the
caloric and fat content of food by weighing or measuring portions and using calorie values and
nutritional labels to determine how many calories and how much fat in each portion. The sample
should include several meals and all food choices offered at those meals. The report should
include what foods a student could choose to provide a reasonable diet to lose weight, for
example a 1,500- or 1,800-calorie a day diet. Is this diet nutritionally sound?
Research indicates that people (both overweight and normal weight) tend to
underestimate the calories in the food they eat, so the caloric value of food in the cafeteria may
be of interest to all your students, even those who are not trying to lose weight.
Changing Eating Habits in School Cafeterias
Eating and Weight
348
and teens? Ask students in they believe the same tips would be effective in their school cafeteria
and restaurants on campus.
Health Literacy and Popular Diets
Social Responsibility and Weight
Gene and Environment Interaction
To give students a clearer picture of how genes and environment interact, students may
benefit by reading a recent study that examines a gene that is associated with an increased risk
for obesity. This research indicated that only people who were physically inactive and had this
gene were at a higher risk for becoming obese.
Cite: Rampersaud, E., Mitchell, B. D., Pollin, T. I., Fu, M., Shen, H., O’Connell, J. R., et
al. (2008). Physical activity and the association of common FTO gene variants with body mass
index and obesity. Archives of Internal Medicine, 168, 1791–1797.
Video Recommendations
Real Women Have Curves is a dramatic film that depicts the pressures to be thin and how one
young Hispanic woman withstands those pressures. Available for DVD rental.
Fast Food Nation is a documentary (based on a book) that examines the health (and
environmental and social) risks of the fast food industry. Available for DVD rental.
Eating and Weight
349
Super Size Me is a documentary that follows one man as he consumed solely fast food for one
month and documents the physical effects on his body. Available for DVD rental.
From Media Education Foundation:
From Films for the Humanities & Sciences:
Diet Confidential: Heavy Marketing with a Dash of Nutrition (2006) examines diet fads and the
modern obsession with slimness. The program considers the role of the media and the marketing
of diet programs, focusing on the Atkins diet.
Food and Obesity: What We Eat (2006) presents the paradox of growing obesity and an
emphasis on thinness by examining the social and psychological meaning of food in our culture.
Body Image for Boys (2002) focuses on the increasing emphasis of body shape for boys and men.
Wasting Away: Anorexia Nervosa (2000) profiles four young women who have anorexia and
their struggle to gain weight and maintain healthy eating.
Having Your Cake: Goodbye to Bulimia (1997) presents the stories of four women who discuss
their experience with bulimia.
Eating and Weight
350
Multiple Choice Questions
1. _________ NOT part of the digestive system.
a. The teeth are
b. The esophagus is
c. The stomach is
d. The bronchioles are
2. Rhythmic contraction and relaxation of the circular muscles that propel food through the
digestive system is known as
a. the esophagus.
b. peristalsis.
c. voluntary digestion.
d. acidic flow.
3. __________ furnish(es) moisture that allows food to be tasted.
a. The esophagus
b. The tongue
c. Salivary glands
d. Teeth
4. ______ propels food through the digestive system, a largely involuntary process.
a. Peristalsis
b. Gastric juices
c. Salivary Glands
d. Parotids
5. Digestion of most types of nutrients occurs in the __________.
Eating and Weight
351
a. large intestine
b. stomach
c. small intestine
d. gall bladder
6. Which system of the body is plagued with more diseases and disorder than any other
system?
a. immune
b. digestive
c. cardiovascular
d. none of the above
7. The principal function of the stomach is to
a. begin the process of digestion.
b. pass digested food into the large intestine.
c. pass digested food into the blood stream.
d. mix food particles with gastric juices.
8. From the stomach, digested food passes into the
a. small intestine.
b. large intestine.
c. anus.
d. blood stream.
9. Stable weight is maintained when
a. a person eats a high-protein diet.
b. the amount of calories expended equals the amount eaten.
c. the calories absorbed by the intestines are half of the number of calories eaten.
d. activity is at a minimum and basal metabolism is at a maximum.
10. ____________ levels fall when fat stores fall, which may provide a long-term signal to
eat more.
a. Leptin
b. Ghrelin
c. Cholecystokinin (CCK)
d. Ventromedial
11. ____________ is a hormone produced by the stomach. Its levels rise before and fall after
meals, which may provide a short-term signal to eat.
Eating and Weight
352
a. Leptin
b. Ghrelin
c. Cholecystokinin (CCK)
d. Ventromedial
12. Production of the peptide hormone cholecystokinin results in
a. feelings of satiation.
b. feelings of hunger.
c. a need to engage in physical activity.
d. depression, anxiety, and loss of energy.
13. The hormone ___________ provides a short-term signal for eating, and ________
provides a long-term signal.
a. insulin . . . CCK
b. leptin . . . insulin
c. serotonin . .. epinephrine
d. ghrelin . . . leptin
14. The relationship between eating and weight maintenance is best described by which of
the following statements?
a. Weight gain is proportional to overeating.
b. A person who eats more than 3,000 calories per day will gain weight.
c. Metabolic rate is a factor in weight maintenance.
d. Fat people eat fewer calories per day than do thin people.
15. The goal of Keys’s project, begun during World War II, was to study
a. the effects of hunger and food deprivation.
b. the rate of weight gain due to systematic overfeeding.
c. the effects of setpoint readjustment with drugs.
d. the optimum ratio of fat to lean body tissue in volunteers.
16. In the study of experimental starvation, what were the effects of semi-starvation on the
behavior of the participants?
a. They showed high group morale and cooperation.
b. They exercised vigorously to distract themselves from feelings of hunger.
c. They became aggressive and lost interest in their normal activities.
d. They became overly attached to other group members.
17. When the participants in the study on experimental starvation were re-fed at the end of
the starvation phase of the experiment,
a. many of them gained more weight than they had lost.
b. most of them were not able to regain lost weight.
Eating and Weight
353
c. they became more cheerful and optimistic than they had been prior to the
starvation phase.
d. they no longer had much interest in food.
18. In Sims’s studies on experimental overeating, some volunteers had trouble returning to
their original weight after the experiment. This problem was associated with
a. family histories of obesity.
b. family histories of diabetes.
c. a permanent change in setpoint brought about by the overeating.
d. a permanent change in blood glucose level.
19. With regard to eating and metabolism, research has shown that
a. overeating changes metabolism.
b. undereating changes metabolism.
c. both overeating and undereating can change metabolism.
d. metabolism is set by genetics and thus cannot be changed.
20. ____________ levels signal low fat stores, prompting individuals to eat.
a. Low leptin
b. High leptin
c. Low insulin
d. High insulin
21. In the study of experimental starvation, the effects of starvation on participants were all
of the following EXCEPT:
a. aggressiveness
b. losing interest in normal activities
c. cooperation with others
d. obsession with food
22. Obesity can result from
a. overeating.
b. slow metabolism.
c. too little physical activity.
d. any or all of these.
23. Carl is five feet, ten inches tall, has a medium frame, and weighs 154 pounds. In other
words, Carl is about in the middle of the ideal weight range according to the Metropolitan
Life Insurance Company’s desirable weight charts. This means that Carl
a. has a healthy waist-to-hip ratio.
b. needs to gain a few pounds.
c. should try to lose a few pounds.
Eating and Weight
d. none of these.
24. The skinfold technique and bioelectrical impedance are ways to measure
a. utilization of glucose by adipose tissue.
b. percentage of body fat.
c. metabolic activity of fat.
d. ratio of height to body weight.
25. The body mass index (BMI)
a. is a measure of total weight.
b. considers both age and gender in calculating obesity.
c. is defined as a person’s height (in meters) divided by body weight (in kilograms)
squared.
d. is defined as body weight (in kilograms) divided by height (in meters) squared.
26. Which of these techniques represents a person’s distribution of body fat?
a. waist-to-hip ratio
b. skinfold technique
c. weight charts
d. water immersion technique
27. Christi is five feet four and has a body mass index of 17.5. Christi could most accurately
be described as
a. extremely thin.
b. somewhat thin
c. average in weight.
d. somewhat heavy.
28. Throughout most of history, being plump or fat
a. was a sign of laziness.
b. was a mark of prosperity.
c. was a signal of poor health.
d. characterized working class people.
29. An analysis of the women who have won the Miss America contest since 1978 showed
what percent of them in the underweight range?
a. 25%
b. 50%
c. 75%
d. 100%
Eating and Weight
30. Most people who see themselves as being overweight are
a. African American women.
b. not sufficiently overweight to be at risk for increased mortality.
c. greatly at risk for increased mortality.
d. both a and c are true.
31. During the past 20 years, Americans have reduced the percent of calories obtained from
dietary fat, and
a. they have become thinner.
b. they have increased their sugar consumption.
c. they have decreased their fast food consumption.
d. their average weight has remained the same.
32. Researchers have suggested several reasons why obesity has increased in the United
States over the past two decades. One possibility is that people are
a. eating more meals at home.
b. increasing their consumption of fast food and sodas.
c. increasing their percentage of dietary fat.
d. decreasing their intake of sugar.
33. The setpoint concept assumes that
a. people have a kind of internal thermostat that regulates weight.
b. gaining weight is easier than losing it.
c. losing weight is easier than gaining it.
d. heredity is unrelated to a person’s weight.
34. From an anthropological perspective, what would be the advantage of a setpoint for fat?
a. Fat storage and retention helped protect people during food shortages.
b. Fat enhanced physical attractiveness and reproduction.
c. Fat helped protect individuals from injuries.
d. Fat made individuals less attractive to predators.
35. How does setpoint influence metabolism during a period of severe food restriction?
a. It increases metabolism.
b. It decreases metabolism.
c. It does not influence metabolism.
d. It increases metabolism in the beginning but decreases metabolism if the food
restriction continues.
Eating and Weight
36. After several weeks on a 500-calorie a day diet, Loraine is constantly hungry, tired, and
not interested in much of anything. According to the setpoint concept,
a. these are the effects of damage to her hypothalamus.
b. she is losing too much muscle tissue.
c. she is below her setpoint.
d. she is still above her setpoint.
37. The results of the studies on experimental starvation and experimental overeating
a. indicate that eating is a learned behavior.
b. suggest that eating is always pleasurable.
c. are consistent with the concept of setpoint.
d. show that eating is relatively unimportant in the lives of most people.
38. The history of the human species has been marked mostly by shortages of food,
a. which would make a “thrifty” metabolism a survival advantage.
b. which lends support to the setpoint concept.
c. which casts doubts on the positive incentive model.
d. which casts doubt on the role of hormones in weight regulation.
39. Studies of adopted children and identical twins have found that
a. genetic factors are important in weight and fat distribution.
b. environmental factors are more important than genetic factors in determining
weight.
c. genetic factors are more important for men, and environmental factors are more
important for women in determining weight.
d. genetic factors are more important for women, and environmental factors are
more important for men in determining weight.
40. According to the positive incentive model of weight control, people
a. will have difficulty weighing either much more or much less than their
biologically determined setpoint.
b. eat for pleasure.
c. are rewarded for having fat children.
d. are punished for having fat children.
41. Nelson enjoys tasty food, and he will eat food even when he isn’t hungry, if he is fond of
that type of food. This eating pattern is most consistent with the _____ model.
a. positive incentive
b. psychodynamic
c. setpoint
d. behavior modification