Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 30 Overweight, Obesity, and Weight Control

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity Historical perspective –Writings as early as 2nd century A.D. Current status –70% of American adults struggle to lose weight. –40 billion/year industry

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity Worldwide epidemic –Obesity is becoming an international problem. –Obesity rates are increasing. –Obesity rates are associated with increases in Diabetes Heart disease

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity No unanimity for terminology –Overweight, overfat, and obesity Progressive long-term process –Manifests over the course of many years of uneven energy balance America: a nation of the overfed

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity: Complex Interaction of Many Factors Genetics Environmental factors Metabolic parameters Behavioral factors Social influences Perhaps racial influences

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Genetics Influences Body Fat Accumulation Difficult to quantify role of genetics and environment Mutant gene –Leptin – hormone that regulates fat metabolism –Leptin normally blunts the drive to eat. –If defective, the satiety signal is not received.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Influence of Racial Factors Differences in food and exercise habits, cultural attitudes toward weight Differences in resting energy expenditure

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity Physical inactivity: crucial component in excessive fat accumulation –Activity correlates inversely with body fat level. Benefits of increased energy output with aging –Active men tend to remain leaner than sedentary counterparts.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity Health risks of excessive body fat –Leading cause of preventable death –Excessive fatness in childhood and adolescence predicts adverse health effects in adulthood.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Obesity Specific health risks –Diabetes– Renal disease –Heart disease– Sleep apnea –Hypertension– Osteoporosis –Stroke –Cancer: breast, colon, esophagus, kidney, uterus, endometrial –Elevated plasma lipids

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Criteria for Excessive Body Fat Percent body fat –Children > 85th percentile skinfold –Men > 20% body fat –Women > 30% body fat

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Regional Fat Distribution Central or android-type obesity Peripheral or gynoid-type obesity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Lipoprotein Lipase Affects Body Fat Distribution LPL plays a role in gender differences in fat patterning. Females have greater LPL activity in hips, thighs, breasts. Males have higher LPL activity in abdomen.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adipocyte Size and Number Fat cell hypertrophy versus hyperplasia Cellularity differences between nonobese and obese persons

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adipose Tissue Effects of weight loss –Adipocyte size decreases, while number remains the same Effects of weight gain –Moderate weight gain results from increased adipocyte size. –Severe weight gain may be accompanied by an increase in adipocyte number.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adipocyte Development Cell size increases as age increases. –Between ages 1 and 6, cell size triples. Cell number –Increases in third trimester and first year of life –Gradual increases to age 10 –Adolescent growth spurt

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Energy Balance: Input Versus Output Dieting for weight control –Long-term success depends on the degree of obesity at the start of intervention.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition National Weight Control Registry: Clues to Success Behavioral approaches to food intake Age 18 or older Maintained at least 30-pound weight loss for 1 year

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Long-Term Success Weight loss improves disease risk biomarkers. –Modest weight loss = health benefit Setpoint theory: a case against dieting –Resting metabolism decreases. –Biologic feedback mechanism

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Dieting Extremes Low carbohydrate-ketogenic diets High-protein diets Semistarvation diets

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Factors that Affect Weight Loss Early weight loss is largely water. Hydration level Longer term deficit promotes fat loss.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Exercise for Weight Control Misconceptions about exercise –Exercise and food intake –Caloric stress of physical activity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Increasing Energy Output More effective than calorie restriction alone Dose–response relationship Exercise and food intake Caloric stress of physical activity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Effectiveness of Regular Exercise Dose–response relationship Walking–running for different durations Exercise frequency Start slowly and progress gradually Self-selected energy expenditures: mode of exercise

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Diet Plus Exercise: The Ideal Combination Spot reduction does not work. –Exercise does not cause fatty acid release from the fat pads directly over the active muscle.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Possible Gender Difference Men appear to respond better to weight loss interventions. May be due to fat patterning

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Weight Loss Recommendations for Wrestlers and Other Power Athletes 5 – 7% body fat is lower limit Increased training Moderate calorie restriction

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gaining Weight: The Competitive Athlete’s Dilemma Goal: gain muscle mass and connective tissue –Unsupported hype Protein supplements Diet supplements Weight gain products

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Increase the Lean, Not the Fat Aerobic exercise decreases fat. Increase protein intake to 1.6 g/kg/day. How much gain to expect –Over a 1-year period ~ 20% increase in lean mass