Chapter 10 Lecture. Health: The Basics Tenth Edition. Reaching and Maintaining a Healthy Weight

Transcription

1 Chapter 10 Lecture Health: The Basics Tenth Edition Reaching and Maintaining a Healthy Weight

2 OBJECTIVES 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.

3 Reaching and Maintaining a Healthy Weight The United States is one of the fattest nations on earth; 63% of adults are overweight. Obesogenic characterizes environments that promote increased food intake, nonhealthful food, and physical inactivity. Overweight refers to having body weight more than 10% above healthy levels. Obesity refers to having body weight more than 20% above healthy levels.

4 Obesity Trends among U.S. Adults, 1990, 2000, and 2010

5 Potential Negative Health Effects of Overweight and Obesity

6 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

7 Factors Contributing to Overweight and Obesity Genetic and Physiological Factors Metabolic Rates 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.

8 Factors Contributing to Overweight and Obesity Genetic and Physiological Factors Hormonal Influences: Ghrelin and Leptin Less than 2% 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.

9 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 billion. An extremely obese person may have 200 billion. Called hyperplasia, this type of obesity begins in childhood, perhaps due 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.

10 Factors Contributing to Overweight and Obesity Environmental Factors Greater Access to High Calorie Foods Prepackaged, high-fat meals, fast food, and sugar-laden soft drinks, high-calorie coffee lattes, and energy drinks Greater consumption of restaurant meals as a result of the growing number of women who work Bottle feeding infants Misleading food labels Larger dishes, cups, and serving utensils

11 Factors Contributing to Overweight and Obesity Environmental Factors Early Sabotage: A Youthful Start on Obesity Children are eating more junk food. Children exercise less than any previous generation. Maternal undernutrition, obesity, and diabetes during gestation and lactation are strong predictors of obesity in children. Race and ethnicity interwoven with environmental factors increase risk for obesity.

12 Factors Contributing to Overweight and Obesity 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 Four in ten adults never engage in any exercise, sports, or physical activity.

13 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.

14 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 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. A new BMI category of 50 or higher known as super obese has been added to obesity designations.

15 Body Mass Index

16 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 0.8 in women indicates health risk.

17 Measures of Body Fat Men's bodies should contain between 8 and 20% total body fat; men who exceed 22% are overweight. Men with a body fat between 3 and 7% are considered underweight. Women should be within the 20 to 30% range; women who exceed 35% are overweight. Women with a body fat between 8 and 15% are considered underweight. Health may be compromised by too little body fat.

18 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 one 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. Find a weight loss plan you can live with

19 Energy Expenditure = Energy Intake

20 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 Weight Loss Surgery A last resort and particularly for people who are severely overweight and have weight-related diseases

21 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.