Chapter 10 Lecture

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Reaching andMaintaining aHealthy Weight

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LEARNING OUTCOMES

• Define overweight and obesity, describe the current epidemic of overweight/obesity in the United States and globally, and understand risk factors associated with these weight problems.

• Describe factors that place people at risk for problems with obesity. Distinguish between factors that can and cannot be controlled.

• Discuss reliable options for determining percentage of body fat and a healthy weight for yourself.

• Discuss the roles of exercise, diet, lifestyle modification, fad diets, and other strategies of weight control, and which methods are most effective.

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Reaching and Maintaining a Healthy Weight

• The United States is among the fattest nations on Earth.

• Obesogenic characterizes environments that promote increased food intake, nonhealthful food, and physical inactivity.

• Overweight refers to having body weight more than 10 percent above healthy levels.

• Obesity refers to having body weight more than 20 percent above healthy levels.

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Some of the World's Most and Least Overweight Countries

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Obesity Trends among U.S. Adults, 1990, 2000, and 2011

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Potential Negative Health Effects of Overweight and Obesity

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Reaching and Maintaining a Healthy Weight (cont.)• Nearly 26 million people have diabetes, which is

associated with being overweight and obese. Another 79 million have prediabetes.

• Diabetes is among the costliest of diseases, with estimated costs over $245 billion per year.

• Globally, more than 1 billion adults and 200 million school-aged children are overweight; 475 million adults and 50 million school-aged children are obese.

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Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors• Genes

– The exact role of genes remains in question.– Obese parents tend to have overweight

children.– Twins raised separately tend to be the same

weight.– Thrifty gene theory

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Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors• Metabolic The basal metabolic rate (BMR) is the minimum rate at

which the body uses energy when at complete rest.– Resting metabolic rate (RMR) includes BMR plus additional

energy expended through daily sedentary activities.– Exercise metabolic rate (EMR) accounts for the remaining

caloric expenditures.• There are many theories about what might affect metabolic

rates.– One theory suggests that the hypothalamus that monitors eating

does not work properly in obese people.– Another suggests that thin people send more effective

messages to the hypothalamus, known as adaptive thermogenesis.

– Set point theory suggests bodies try to maintain weight within a narrow range or at a set point.

– Yo-yo diets are cycles in which people diet and regain weight.

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Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors• Hormonal Influences: Ghrelin and Leptin

– Less than 2 percent of obese people have a thyroid problem.

– Ghrelin, the hunger hormone, may play a role in appetite stimulation.

– Leptin, an appetite regulator produced by fat cells, increases in the blood as fat tissue increases. Receptors do not seem to work well in obese people.

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Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors• Fat Cells and Predisposition to Fatness

– Some obese people may have an excessive number of fat cells.• A normal weight individual has between 25 and 35

billion. • A moderately obese individual may have 60–100

billion. • An extremely obese person may have 200 billion.

– Called hyperplasia, this type of obesity begins in childhood, perhaps owing to the mother's dietary habits.

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Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)

• Critical periods for development of hyperplasia are the last 2–3 months of fetal development.

– This theory suggests that the number of fat cells does not increase in adulthood, but the ability of the cells to swell (hypertrophy) and shrink does occur.

– Weight gain may be tied to both the number of fat cells in the body and the capacity of individual cells to enlarge.

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Factors Contributing to Overweight and Obesity—Environmental Factors• Greater Access to High-Calorie Foods

– Advertising promotes eating, emphasizing good taste over the poor nutritional value of what is being sold.

– Super-sized portions are the norm.– Increased reliance on restaurant and

convenience foods.– Misleading food labels– Fast-food restaurants, cafes, vending

machines, and quick-stop markets.

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Factors Contributing to Overweight and Obesity—Environmental Factors (cont.)• Early Sabotage: A Youthful Start on Obesity

– Over 17 percent of all children and adolescents are now obese.

– Sedentary activities (social media, video games, television) have replaced vigorous physical activity.

– It may be too dangerous for children to walk to parks and schools.

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Factors Contributing to Overweight and Obesity—Environmental Factors (cont.)

– Maternal nutrition, obesity, and diabetes during gestation and lactation may play a role in predisposing the fetus to becoming overweight.

– Race and ethnicity interwoven with environmental factors increase risk for obesity.

– Obesity stigma is a major threat to overweight and obese children's self-esteem.

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Factors Contributing to Overweight and Obesity—Environmental Factors (cont.)• Psychosocial and Economic Factors

– Eating may soothe fears, sadness, and worry for some.

– Socioeconomic factors can provide obstacles or aids to weight control.

• Lack of Physical Activity– One third of adults never engage in any

exercise, sports, or physical activity.

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Assessing Body Weight and Body Composition• Some body fat is essential for health.

– Essential fat is needed for the maintenance of life and reproductive functions.

– Storage fat, the nonessential fat, makes up the remainder of the fat reserves.

– Being underweight, or having extremely low body fat, can cause problems.

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Body Mass Index (BMI)

• A description of body weight relative to height that is highly correlated with total body fat.

• It is not gender specific and does not measure a percentage of body fat, but rather provides a measure of being overweight and obese rather than just weight alone.

• Calculated by dividing by weight in kilograms by your height in meters squared.

• Healthy weight is a BMI between 18.5 and 24.9; 25 to 29.9 indicates overweight, and over 30 is obese. Over 40 is morbidly obese.

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Body Mass Index

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Limitation of BMI

• Water, muscle and bone mass are not included in BMI calculations.

• BMI levels don't account for the fact that muscle weighs more than fat, meaning a well-muscled person could be classified as obese.

• People who are under 5 feet or are older, have little muscle mass and so BMI levels can be inaccurate.

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Youth and BMI

• Over 17 percent of youth are obese.• BMI ranges above normal weight are labeled as

"at risk for overweight" and "overweight" to avoid the sense of shame that words like "obese" and "morbidly obese" may cause.

• BMI ranges for children and teens take into account normal differences between boys and girls.

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Waist Circumference and Ratio Measurements• Where you carry fat may be more important than

how much you carry.• Abdominal fat is more threatening than fat in

other regions.• A waistline greater than 40 inches in men and 35

inches in women may be indicative of health risk.

• A waist-to-hip ratio greater than 1 in men and greater than 0.8 in women indicates health risk.

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Measures of Body Fat

• Men's bodies should contain between 8 and 20 percent total body fat; men who exceed 22 percent are overweight.

• Men with a body fat measurement between 3 and 7 percent are considered underweight.

• Women should be within the 20 to 30 percent range; women who exceed 35 percent are overweight.

• Women with a body fat measurement between 8 and 15 percent are considered underweight.

• Health may be compromised by too little body fat.

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Body Fat Percentage Norms for Men and Women

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Overview of Various Body Composition Methods

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Managing Your Weight

• Improve your eating habits– What causes you to eat? What are your

triggers?– Seek assistance from professionals or

reputable sources.• Understand calories and energy balance

– 3,500 extra calories results in an extra 1 pound of storage fat.

• Include exercise– Increasing BMR, RMR, or EMR will help burn

calories.– Increasing your muscle-to-fat tissue ratio will

burn more calories.

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Avoid Trigger-Happy Eating

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Analyzing Popular Diet Programs

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Analyzing Popular Diet Programs (cont.)

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ABC News Video: Keeping it Off

Discussion Questions• Discuss the practical methods used for keeping

weight off. • Discuss psychological factors or contributors for

the inability to maintain weight loss. • What tips would you give someone who wanted

to lose weight safely and to maintain weight loss?

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Energy Expenditure = Energy Intake

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Some Perspective on Weight Control EffortsConsidering Drastic Weight-Loss Measures• Very-Low-Calorie Diets

• Must be medically supervised• Formulas with daily values of 400 to 700 calories• Can cause significant health risks• Ketoacidosis is one potentially dangerous complication

• Drug Treatment• FDA approval is not required for over-the-counter "diet aids"

or supplements• Dangerous side effects and potential for abuse

• Surgery• A last resort and particularly for people who are severely

overweight and have weight-related diseases

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ABC News Video: Best Diet Plan Apparently Works

Discussion Questions• Why do you think the Weight Watchers program

has been so successful? What role does social support play in the program?

• What are some recommendations or strategies for those who want to lose weight but cannot afford Weight Watchers?

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Trying to Gain Weight

• Determine why you cannot gain weight; reasons may be metabolic, hereditary, psychological, and others.– Perhaps you are an athlete and burn more

calories than you consume.– Perhaps you are stressed and skip meals.– Older adults lose the sense of taste and

smell, making eating less pleasurable.– Visual and dental problems may make eating

more difficult.

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Tips for Gaining Weight

• Eat more frequently• Put extra spreads (peanut butter, cream cheese,

or cheese) on your foods.• Take seconds whenever possible.• Add high-calorie drinks such as whole milk.• Eat with people you are comfortable with.• Exercise can increase appetite; moderate

extreme exercise.• Avoid diuretics, and relax.