1. Chapter 10: Reaching and Maintaining a Healthy Weight
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2. Learning Outcomes
Describe the current epidemic of overweight/obesity in the United States and globally, and demonstrate understanding of health risks associated with excess weight.
Describe factors that put people at risk for problems with obesity, distinguishing between controllable and uncontrollable factors.
Discuss reliable options for determining a healthy weight and body fat percentage.
Explain the effectiveness and potential pros/cons of various weight control strategies, including exercise, diet, lifestyle modification, supplements/diet drugs, surgery, and other options.
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3. Overweight and Obesity: A Growing Challenge
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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4. Obesity in the United States
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5. Obesity in the United States
More than 69 percent of U.S. adults overall are overweight or obese.
Obesity rates are 34 percent for men and 36 percent for women, and rates of extreme obesity are on the rise.
Rates vary among ethnicities, with between 51% and 68% of Asian Americans at a healthy weight.
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6. Potential Negative Health Effects of Overweight and Obesity
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7. Overweight and Obesity: A Growing Challenge (cont.)
Nearly 29 million people have diabetes, which is associated with being overweight and obese. Another 86 million have prediabetes.
Diabetes is among the costliest of diseases.
More than 2.1 billion people, almost 30 percent of the world's population, are overweight or obese—more than 2.5 times the number of people who are undernourished.
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8. 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.
An important gene, FTO, regulates the hormone ghrelin—a key factor in eating behavior.
Effects of the FTO gene on obesity is over 30 percent less among the most physically active adults (those engaging in 90 minutes each day).
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9. Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)
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.
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10. Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)
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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11. Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)
Hormonal Influences: Ghrelin and leptin
Less than 2 percent of obese people have a thyroid problem.
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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12. Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)
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.
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13. Factors Contributing to Overweight and Obesity—Genetic and Physiological Factors (cont.)
Called hyperplasia, this type of obesity begins in childhood, perhaps owing to the mother's dietary habits.
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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14. 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.
Super-sized portions are the norm.
Widespread availability of high calorie coffee and sugary drinks
Increased reliance on restaurant and convenience foods
Bottle feeding instead of breast feeding
Misleading food labels
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15. 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
Behavioral Risk Factor Surveillance System (BRFSS) survey indicated only 21% percent of adults engaged in enough aerobic and muscle strengthening exercise to meet guidelines.
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16. 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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17. Body Mass Index (BMI)
BMI is body weight described relative to height that is highly correlated with total body fat.
Not gender specific, does not measure a percentage of body fat; provides a measure of being overweight and obese rather than just weight alone.
Calculated by dividing weight in kilograms by height in meters squared.
BMI weight categories:
Healthy weight: 18.5 to 24.9
Overweight: 25 to 29.9
Obese: over 30 is obese
Morbidly obese: over 40
Super obese: BMI of 50 or higher—one increasing in numbers
Under 18.5 is considered underweight.
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18. Body Mass Index (BMI)
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19. Limitations 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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20. Youth and BMI Over 30 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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21. 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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22. 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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23. Body Fat Percentage Norms for Men and Women
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24. Overview of Various Body Composition Assessment Methods
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25. Managing Your Weight: Individual Roles
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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26. Energy Expenditure = Energy Intake
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27. Some Perspective on Weight Control Efforts Considering 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
Prescription option;, Belviq, Qsymia, and Contrave; are controversial and carry warnings.
Surgery
A last resort and particularly for people who are severely overweight and have weight-related diseases
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28. 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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29. Trying to Gain Weight (cont.)
Examine diet and exercise behaviors
Take steps and use recommended strategies to achieve and maintain a healthy weight.
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