© 2007 Thomson - Wadsworth Chapter 9 Weight Management

© 2007 Thomson - Wadsworth

Chapter 9

Weight Management


Ask Yourself

1. The less you weigh, the better it is for your health.

2. Obese people pay higher insurance premiums than thin people.

3. If you weigh too much according to the scales and the so-called ideal weight tables, you are too fat.

4. If you are too fat, it is because you eat too much.

5. Basal metabolism contributes only a small percentage of a person’s daily energy output.


Ask Yourself

6. It is probable that the most important single contributor to the obesity problem in our country is under activity.

7. Any food can make you fat, even carrot sticks, if you eat enough of them.

8. A properly designed diet and exercise program can make you lose weight faster than a total fast.

9. Fad diets are popular because their followers achieve quick and permanent weight loss.

10. Anorexia nervosa is a disease in which a person has no appetite.


A Closer Look at Obesity

Bodies come in many shapes and sizes. Which are healthy?


A Closer Look at Obesity

F I G U R E 9 – 1: TRENDS IN PREVALENCE OF OVERWEIGHT AND OBESITY AMONG CHILDREN AND ADULTS,UNITED STATES, 1988 TO 2002


A Closer Look at Obesity• Food portion sizes and obesity rates have grown in

parallel.• Vending machines selling soft drinks, high-fat snacks, and

sweet snacks are common in schools and workplaces.• Adults spend more time in sedentary activities, such as

watching television or commuting to and from work and school.

• Children watch 12 to 14 hours of television a week and spend 7 hours playing video games.

• Schools offer fewer physical education classes for children.• Increasing numbers of families live in communities

designed for car use, unsuitable and often unsafe for activities such as walking, biking, and running.


A Closer Look at Obesity• Overweight:

conventionally defined as weight between 10% and 20% above the desirable weight for height, or a body mass index (BMI) of 25.0 through 29.9.

• Obesity: conventionally defined as weight 20% or more above the desirable weight for height, or a BMI of 30 or greater.

Fact:• Obesity rates are higher

than ever. Currently, 65% of adults

and approximately 16% of children and adolescents in the U.S. are either overweight or obese—exceeding their healthy weight range.

• Annual cost of overweight and obesity exceeds $117 billion a year. Direct costs (treatment) Indirect costs (lost

productivity, disability, morbidity & mortality)


Problems Associated with Weight

• Compare the maps on the next 4 slides…

• Note the increasingly upward trend of obesity among the 50 states

• 1991 – no states had obesity rate > 40%, only 4 states > 15%

• 2000 – only Colorado was < 15%, 22 states > 20%

• 2004 – 7 states 15-19%, 33 states 20-24%, 9 states > 25%








Problems Associated with Weight

• Underweight: 10% or more below the desirable weight for height, or a BMI of less than 18.5.An individual whose weight is too low has

minimal body fat stores.Will be at a disadvantage in situations

where energy reserves might be needed, such as a prolonged period of physiological stress or injury.

Other problems include menstrual irregularity, infertility, and osteoporosis.


Healthful Weight?

• Problems of defining a healthful weight are many. For long-distance runners, unneeded

pounds are a disadvantage.For swimmers, fat contributes to their

buoyancy and insulates them against the cold.

Dancers and models may value thinness so highly that to attain it, they compromise their health.

• What range is compatible with wellness and long life?


Healthful Weight?Body Weight versus Body Fat• Two people of the same sex, age, and height may both

weigh the same, yet one may be too fat and the other too thin. Here are some ways that is possible: The difference lies in their body composition. One may have small, light bones and minimally

developed muscles, while the other has big, heavy bones and well-developed muscles.

• The health risks for obesity refer to people who are overfat.

• Desirable measures for percent body fat: Men 12-20% (overfat would be >25%) Women 20-30% (overfat would be >33%)


Healthful Weight?

Measuring Body Density

• Underwater weighing (hydrostatic weighing): a measure of density and volume; the less a person weighs underwater compared to the person’s out-of-water weight, the greater the proportion of body fat (fat is less dense or more buoyant than lean tissue).


Healthful Weight?

Measuring Body Density

• Body density can more easily be determined by air displacement methods.The BodPod measures

the volume of air displaced by a person when seated in a sealed device of known volume.


Healthful Weight?

Measuring Body Fat• Skinfold test: Using a

caliper to measure the thickness of a fold of fat, the measurement is then applied to a standard table to give a fair approximation of total body fat.


Healthful Weight?

Measuring Body Fat• Dual energy X-ray

absorptiometry (the DEXA test) can yield an accurate image of the body’s fat-free tissue

and total fat content.


Healthful Weight?

Measuring Body Fat• Bioelectrical impedance:

estimation of body fat content made by measuring how quickly electrical current is conducted through the body. It provides a measure of

how much fat a person has by measuring the speed at which a slight electrical current is conducted through the body (from the ankle to the wrist).


Healthful Weight?

Distribution of Fat

• Central obesity: excess fat on the abdomen and around the trunk. “Apple-shaped” body Strong risk factor for

type 2 diabetes, heart disease, hypertension, and other problems.

• Peripheral obesity: excess fat on the arms, thighs, hips, and buttocks.


Healthful Weight?

Weighing In for Health• A person’s health risk is dependent on three factors:

Body weight Amount and location of body fat Current health status

• Body mass index: an index of a person’s weight in relation to height that correlates with total body fat content. Keep in mind that BMI does not account for:

• Location of fat in the body• Fact that a muscular person with a low

percentage of body fat may have a high BMI



Understanding BMI


Benefits of Using BMI:

• BMI correlates strongly with body fatness and risk of disease and death


Understanding BMI

Cautions in Using BMI:• May overestimate body

fat in athletes and underestimate body fat in adults over 65.

• A muscular person, such as this body builder, often has a low percentage of body fat but a high BMI.


Healthful Weight?

• Waist circumference: a measure used to assess abdominal (visceral) fat; excess fat in the abdomen increases a person’s risk for health problems.

• Waist circumference denoting risk of obesity-related health problems:Men > 40”Women > 35”


Energy Balance


Energy Balance• The body expends most of its

energy on basal metabolism—maintaining basic physiological processes such as breathing, heartbeat, and other involuntary activities.

• The second largest amount of energy is expended for voluntary physical activities—an amount that will vary by activity level.

• A minor amount of energy is also used for the thermic effect of food— the energy needed to digest, absorb, and process the food you eat.

HOW THE BODYEXPENDS ENERGY


Energy Balance• Basal metabolism: the sum

total of all the chemical activities of the cells necessary to sustain life, exclusive of voluntary activities—that is, the ongoing activities of the cells when the body is at rest.

• Basal metabolic rate (BMR): the rate at which the body spends energy to support its basal metabolism. The BMR accounts for the largest component of a person’s daily energy (calorie) needs.


Energy Balance

• Body composition influences metabolic rate. Weight training can

help shift your body composition toward more lean tissue, thereby speeding up your metabolism.



Causes of Obesity

Genetics• Set-point theory: the theory that the body tends to

maintain a certain weight by adjusting hunger, appetite, and food energy intake on the one hand and metabolism (energy output) on the other so that a person’s conscious efforts to alter weight may be foiled.

• An identified gene—named ob (for obese) Appears to produce a hormone called leptin, (Greek

word for slender) It has been reported that as body fat stores increase,

blood leptin increases.


Causes of Obesity

GeneticsFat cell theory: states that during the growing years, fat

cells respond to overfeeding by producing additional fat cells; the number of fat cells eventually becomes fixed, and overfeeding from this point on causes the body to enlarge existing fat cells.

• Fat cells of obese people contain higher levels of the enzyme lipoprotein lipase (LPL), which determines the rate at which adipose cells store fat. Lipoprotein lipase (LPL): an enzyme located on

the surfaces of fat cells that enables the cell to convert blood triglycerides into fatty acids and glycerol to be pulled into the cell for reassembly and storage as body fat.

The larger the fat cell (and the greater the number of fat cells), the more LPL and the more easily the body can pull triglycerides into fat cells for storage.


Causes of Obesity

Environment• External cue

theory: the theory that some people eat in response to such external factors as the presence of food or the time of day rather than to such internal factors as hunger.


Causes of Obesity

A Closer Look at Eating Behavior• Hunger: the physiological drive to find and

eat food, experienced as an unpleasant sensation.

• Appetite: the psychological desire to find and eat food, experienced as a pleasant sensation, often in the absence of hunger.

• Satiety: the feeling of fullness or satisfaction that people feel following a meal.


Causes of Obesity• Hypothalamus (high-

poh-THALL-ah-mus): a part of the brain that senses a variety of conditions in the blood, such as temperature, salt content, and glucose content, and then signals other parts of the brain or body to change those conditions when necessary.

• Arousal: as used in this context, heightened activity of certain brain centers associated with excitement and anxiety.


Weight Gain and Loss

Weight Gain and Loss• Changes in body

weight can reflect shifts in fat, fluid, bone minerals, and lean tissues (e.g. muscles).

• Most quick weight-loss diets promote large losses of fluid with little or no real loss of body fat.



Weight Gain• When you eat more calories than you

need, where does this excess go in your body?The energy nutrients…

•carbohydrate •fat•protein

…contribute to body stores



F I G U R E 9 – 5

FEASTING AND FASTING: In A, the person is storing energy.



F I G U R E 9 – 5

FEASTING AND FASTING: In B, the person is drawing on stored energy.



F I G U R E 9 – 5

FEASTING AND FASTING: In C, the person is in ketosis.



• Ketosis (kee-TOE-sis): an adaptation of the body to prolonged (several days’) fasting or carbohydrate restriction.Body fat is converted to ketones,

which can be used as fuel for some brain cells.• Indirectly, the nervous system begins to

feed on the body’s fat stores and reduces the need for glucose.

• This spares the muscle and lean tissue from being devoured and prolongs starvation.



• KetosisMay be harmful by upsetting the acid-base

balance of the blood.The body’s lean tissue continues to be lost

at a rapid rate.The body becomes conservative and slows

the process of metabolism.• Requires even fewer calories


Dieting is big business in theUnited States.

•Promotion of diet books, products and programs.•One-third of American adults are on a diet.

Although most diets canprovide a weight loss in theshort term, few people canlose weight and keep it off.

Some diets may be harmful.




Evaluating Diets

• Systematically eliminates groups of foods. Probably lacking in nutrients. Hard to adhere to the eating plan.

• Encourages specific supplements of foods only available from selected distributor. May contain harmful or unproven ingredients.

• Touts magic or miracle foods that burn fat. The only way to “burn” fat is to increase physical

activity or decrease the amount of calories consumed.

• Promotes bizarre quantities of one food or type of food. Not good advice, considering human nutritional

needs.


Evaluating Diets

• Has a rigid menu No one diet plan will work for everyone.

• Promotes specific food combinations. Needlessly restricts dietary intake and choices.

• Promises weight loss of more than two pounds per week A safe weight loss goal = 0.5-2.0 pounds/week

• Provide warnings for people with health conditions such as diabetes and hypertension.

• Does the program encourage/promote physical activity?


Evaluating Diets

• Does the program encourage an intake very low in calories? Designed for persons with

severe obesity or health problems.

Needs vitamin and mineral supplementation.

Observed for adverse health effects.




Surgery• Gastroplasty surgery: sugery on the stomach

(also called stomach stapling) that reduces its volume to less than 2 ounces (the size of a shot glass) to prevent overeating.

• Liposuction: a type of surgery (also called lipectomy) that vacuums out fat cells that have accumulated, typically in the buttocks and thighs. If large calorie intake is continued without

expenditure through physical activity, fat will return to the fat cells that remain in those regions.



Weight Loss Strategies

• The secret is a sensible (not to say easy) three-pronged approach involving:Healthful eating habitsExerciseBehavior change

• Such an approach takes tremendous dedication.

• Many of those who complete weight loss programs lose about 10% of their body weight, only to regain two-thirds of it back within 1 year and almost all of it back within 5 years.


1. Adopt a nondiet approach to weight loss.2. Set achievable goals.3. Focus on health rather than appearance.



Individualize Your Weight Loss Plan

• Find the plan that is right for you.• Think of it as an eating plan that you

will adopt for life.• A calorie deficit of 500 calories/day for

seven days is enough to lose one pound of body fat a week.Spending an extra 250 calories per day by

exercising will increase the calorie deficit.







• Aim for gradual weight loss.• Expect to reach a plateau.• Aim for a positive gain in lean body

mass.• Weight loss and bone health.

Include adequate calcium and weight-bearing exercise.

• Adopt a physically active lifestyle.





Weight Gain Strategies• The healthful way to gain

weight is to build yourself up by patient and consistent training while eating nutritious foods containing enough calories to gain weight. Choose calorie-dense

snacks. Eat more frequently. Spend more time eating

each meal: Start with the calorie-dense food first, finish with dessert.

Eat regular, balanced meals. Eat more food and add

extra calories.


• Examine your options.• Take the edge off hunger

with an appetizer…• Make specific requests:

reduced and fat-free dressings…

• Request fresh fruit for dessert…

• Hold the sauce or order red sauces rather than white…

• Inquire about preparation…

• Downsize your order.• Order a special omelet:

egg substitute...• Watch out for

overindulgence • Take time to enjoy your

meal…


• Sandwich Shop: Fresh sliced veggies in a pita with low-fat dressing…

• Rotisserie Chicken: Chicken breast (remove skin), steamed vegetables…

• Fast Food: Grilled chicken breast sandwich (no sauce)…

• Salad Bars: Broth-based soups, fresh greens, low-fat dressing…

• Asian Take-Out: Wonton soup, steamed vegetable mixtures over rice or noodles…

• Pizza Night: Choose flavorful, low-fat toppings such as peppers, onions…

Eating Well on the Run


Breaking Old Habits



Breaking Old Habits

• Behavior modification – a process developed by psychologists for helping people make lasting behavior changes



The Eating Disorders

• Eating disorder: general term for several conditions: Anorexia nervosa Bulimia nervosa Binge-eating disorder

…that exhibit an excessive preoccupation with: Body weight Fear of body fatness Distorted body image


Anorexia nervosa: Literally “nervous lackof appetite,” a disorder(usually seen in teenagegirls) involving self-starvationto the extreme.

an = withoutorexis = appetite

For many people with anorexia nervosa, a full day’s diet may consist of no more than 3 or 4 items




• Bulimia nervosa, bulimarexia (byoo- LEE-me-uh, byoo-lee-ma-REX-ee-uh): binge eating (literally, “eating like an ox”). Combined with an intense fear of becoming fat and usually followed by self-induced vomiting or the taking of laxatives.buli = ox



Bulimia nervosa• Two types:

Purging type: the person regularly engages in self-induced vomiting or the misuse of laxatives, diuretics, or enemas.

Nonpurging type: the person uses other behaviors, such as fasting or excessive exercise, but does not regularly engage in self-induced vomiting or the misuse of laxatives, diuretics, or enemas.



• Binge-eating disorder: an eating disorder characterized by uncontrolled chronic episodes of overeating (compulsive overeating) without other symptoms of eating disorders. Typically, the episodes

of binge eating occur at least twice a week on average for a period of six months or more.




• Disordered eating: eating food as an outlet for emotional stress rather than in response to internal physiological cues.

• Unspecified eating disorders: some people suffer from unspecified eating disorders; that is, they exhibit some but not all of the criteria for specific eating disorders.



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© 2007 Thomson - Wadsworth Chapter 9 Weight Management