The document discusses several genetic and environmental factors that can contribute to obesity. Genetics play a role through genes that influence appetite and fat storage. Having an obese parent increases one's chance of obesity by 30-70%. Environmental factors include overeating high-calorie foods, large portion sizes, sedentary lifestyles, and neighborhood obstacles to physical activity. Reasonable weight loss strategies include modest calorie reduction, increased physical activity, behavior modification, and lifestyle changes that can be maintained long-term.
Answer: Leptin is a hormone produced by fat cells in proportion to the amount of fat stored that decreases appetite and increases energy expenditure. Increased leptin production stimulated by a gain of body fat produces fat loss; a decline in leptin in response to body fat loss results in increased appetite and decreased energy expenditure relative to normal, and thus fat gain. Leptin resistance (analogous to insulin resistance) is the theorized condition of obese people that prevents them from feeling satiated and losing fat in response to their increased circulating leptin. In other words, it is the condition of ignoring leptin’s instructions to decrease appetite. Researchers speculate that obese people, most of whom have high blood levels of leptin, must exhibit lepin resistance since the leptin is ineffective in regulating their weight.
Answer: The fat cells shrink in size, but not in number, which may increase susceptibility to rapid weight regain.
Figure 7-2 Fat Cell Development
Fat cells are capable of increasing their size by 20-fold and their number by several thousand-fold.
Answer: Hunger is the physiological need to eat, programmed by heredity, whereas appetite is the psychological desire to eat, influenced by conscious thought, emotions, and cues in the environment. Satiation is the feeling of fullness that develops during a meal and halts eating; satiety is the sustained feeling of fullness after a meal that inhibits eating until the next meal.
Answer: Food deserts are urban and rural low-income areas with limited access to affordable and nutritious foods (i.e., areas without grocery stores that sell healthy foods the residents can afford).
Table 7-1 National Goals to Combat Obesity
Source: Adapted from: Institute of Medicine (U.S.) Committee on Accelerating Progress in Obesity Prevention, Accelerating Progress in Obesity Prevention: Solving the Weight of the Nation (Washington, D.C.: National Academies Press, 2012), available at www.nap.edu.
Table 7-3 Daily Amounts from Each Food Group for 1200- to 1800-kCalorie Diets
Figure 7-3 Energy Density
Decreasing the energy density (kcal/g) of foods allows a person to eat satisfying portions while still reducing energy intake. To lower energy density, select foods high in water or fiber and low in fat.
Selecting grapes with their high water content instead of raisins increases the volume and cuts the energy intake in half.
Even at the same weight and similar serving sizes, the fiber-rich broccoli delivers twice the fiber of the potatoes for about one-fourth the energy.
By selecting the water-packed tuna (on the right) instead of the oil-packed tuna, a person can enjoy the same amount for fewer kcalories.
Table 7-4 Physical Activity Strategies for Weight Management
Answer: A combination of moderate to vigorous aerobic physical activity along with resistance training at a safe level.
Figure 7-4 Food and Activity Diary
The entries in a food and activity diary should include the times and places of meals and snacks, the types and amounts of foods eaten, and a description of the individual’s feelings when eating. The diary should also record physical activities: the kind, the intensity level, the duration, and the person’s feelings about them.
Table 7-7 Weight-Loss Strategies
Table 7-8 Weight-Gain Strategies
Table NP7-1 Tips for Identifying Fad Diets and Weight-Loss Scams