powers6_ppt_ch18

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Published on December 3, 2008

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Chapter 18 Body Composition and Nutrition for Health : Chapter 18 Body Composition and Nutrition for Health EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6th edition Scott K. Powers & Edward T. Howley Objectives : Objectives 1. Identify U.S. Dietary Goals relative to Carbohydrates and fats as a percent of energy intake Salt and cholesterol Saturated and unsatured fats 2. Contrast the dietary Goals with the Dietary Guidelines 3. Describe Recommended Dietary Allowance (RDA) and Dietary Reference Intakes (DRI), and how they relate to the Daily Value (DV) used in food labeling 4. List the classes of nutrients Objectives : Objectives 5. Identify the fat- and water-soluble vitamins, describe what toxicity is, and which class of vitamins is more likely to cause this problem 6. Contrast major minerals with trace minerals, and describe the role of calcium, iron, and sodium in health and disease 7. Identify the primary role of carbohydrates, two major classes, and the recommended changes in the American diet to improve health status 8. Identify the primary role of fat and the recommended changes in the American diet to improve health status Objectives : Objectives 9. List the food groups and major nutrients representated in the Food Guide Pyramid 10. Describe the Exchange System of planning diets and how it differs from the Food Guide Pyramid 11. Describe the limitation of the height/weight table in determining body composition 12. Provide a brief description of the following methods of measuring body composition: isotope dilution, photon absorptiometry, potassium~40, hydrostatic (underwater weighing), dual energy x-ray absorptiometry, near infrared interactance, radiography, ultrasound, nuclear magnetic resonance, total body eletrical conductivity, bioeletrical imperdance analysis, and skinfold Objectives : Objectives 13. Describe two two-component models of body composition and the assumptions made about the density values for the fat-free mass and the fat mass; contrast this with the multicomponent model 14. Explain the principle underlying the measurement of whole-body density with underwater weighing, and why one must correct for residual volume 15. Explain why there is an error of +2.0% in the calculation of percent body fat with the underwater weighing technique 16. Explain how a sum of skinfolds can be used to estimate a percent body fatness value Objectives : Objectives 17. List the recommended percent body fatness values for health and fitness for males and females, and explain the concern for both high and low values 18. Discuss the reasons why the average weight at any height (fatness) has increased, while deaths from cardiovascular diseases have decreased 19. Distinguish between obesity due to hyperplasia of fat cells and that due to hypertrophy of fat cells 20. Describe the roles of genetics and environment in the development of obesity 21. Explain the set point theory of obesity, and give an example of a physiological & behavioral control system Objectives : Objectives 22. Describe the pattern of change in body weight and caloric intake over the adult years 23. Discuss the changes in body composition when weight is lost by diet alone versus diet plus exercise 24. Describe the relationship of the fat-free mass and colaoric intake to the BMR Nutritional Goals : Nutritional Goals U.S. Dietary Goals (1977) Increase carbohydrate intake to 55-60% total calories Decrease fat intake to fewer than 30% total calories Saturated fat fewer than 10% total calories Decrease dietary cholesterol to 300 mg per day Reduce sugar consumption to 15% total calories Decrease salt intake to about 3 grams per day Dietary Guidelines Selection of foods to meet the Dietary Goals Standards of Nutrition : Standards of Nutrition Dietary Reference Intakes (DRIs) Quantity of nutrients needed for proper function and health Recommended Daily Allowances (RDA) Quantity of each nutrient to meet the needs of most healthy persons Previously did not provide recommendations for carbohydrate and fat intake Standards of Nutrition : Standards of Nutrition Estimated Energy Requirement (EER) Average dietary energy intake predicted to maintain energy balance considering, age, gender, weight, height, and level of physical activity Daily Value (DV) Standard used in nutritional labeling Percentage of recommended intake in each serving Based on a 2,000 kcal•day-1 diet Example of a Food Label : Example of a Food Label Fig 18.1 Classes of Nutrients Water : Classes of Nutrients Water Absolutely essential for life Body is 50-75% water Loss of only 3-4% body water affects performance Water loss Normally ~2,500 ml per day Temperature and exercise can increase water loss to 6-7 liters per day Water intake Beverages (1,500 ml) Solid food (750 ml) Metabolic processes (250 ml) Classes of Nutrients Vitamins : Classes of Nutrients Vitamins Fat-soluble vitamins A, D, E, K Can be stored in the body Excess intake can be toxic Water-soluble vitamins Thiamin, riboflavin, niacin, B-6, folic acid, B-12, pantothenic acid, biotin, C Involved in energy metabolism Vitamin C Maintenance of bone, cartilage, and connective tissue Classes of Nutrients Minerals : Classes of Nutrients Minerals Major minerals and trace elements Calcium Important in teeth and bone structure Osteoporosis Iron Component of hemoglobin Anemia Sodium Associated with hypertension In sodium-sensitive individuals Classes of Nutrients Minerals : Classes of Nutrients Minerals Major minerals Calcium Sodium Phosphorus Magnesium Sulfur Potassium Chloride Trace elements Iron Iodine Fluoride Zinc Selenium Copper Cobalt Chromium Manganese Molybdenum Arsenic Nickel Vanadium Classes of Nutrients Carbohydrates : Classes of Nutrients Carbohydrates Sugars and starches Contain 4 kcals•gram-1 Major energy source Crucial for red blood cells and neurons Dietary fiber Non-digestible Soluble and insoluble forms Recommendations Increase dietary fiber and complex carbohydrate intake Decrease simple sugar intake Classes of Nutrients Fats : Classes of Nutrients Fats Dietary fats Triglycerides Phospholipids Cholesterol Important energy source Contain 9 kcals•gram-1 Recommendations Decrease total fat, saturated fat, and cholesterol intake Classes of Nutrients Proteins : Classes of Nutrients Proteins Not a major source of energy 4 kcals•gram-1 High quality proteins contain the nine essential amino acids Cannot be synthesized by the body Most Americans meet protein intake requirements 0.8 grams•kg-1 body weight Requirements may be higher in athletes Meeting the Guidelines and Achieving the Goals : Meeting the Guidelines and Achieving the Goals Daily food selections to meet RDA for nutrients, vitamins, and minerals 3-5 servings of vegetables 2-4 servings of fruit 6-11 servings of breads, cereals, rice, pasta 2-3 servings of milk, yogurt, cheese 2-3 servings of meats, poultry, fish, dry beans and peas, eggs, nuts Food Group Plans : Food Group Plans Food guide pyramid Provides guidance for selecting foods to meet needs Based on nutrient density The nutrient content of 1,000 kcals of food High nutrient density foods are high in nutrients and low in calories Exchange system Based on: Caloric content and percent of carbohydrate, fat, and protein in each food Rather than on nutrient density Valuable for weight control The Food Guide Pyramid : The Food Guide Pyramid Fig 18.2 Methods of Determining Body Composition : Methods of Determining Body Composition Metropolitan Life Insurance Company’s height/weight tables Percentage above recommended weight Body mass index (BMI) Weight (kg)  height (m2) Problems with these methods No way to tell actual body composition A very muscular person could be classified as obese Body Composition Measurement : Body Composition Measurement Total body water Isotope dilution Bioelectrical impedance analysis (BIA) Bone density Photon absorptiometry Lean tissue mass Potassium-40 Body Composition Measurement : Body Composition Measurement Whole body density Underwater weighing Thickness of various tissues Skinfolds Ultrasound Radiography Models of Body Composition : Models of Body Composition 2-component Fat-free mass and fat mass 3-component Body water, protein + mineral, and fat Body water + protein, mineral, and fat 4-component Mineral, water, protein, fat The 4-component model is the most accurate The 2-component Model : The 2-component Model Underwater weighing Based on body density Fat tissue is less dense than fat-free tissue Use equation to convert body density to percent fat based on age, gender, and race The 2-component Model : The 2-component Model Skinfolds Thickness of subcutaneous fat is measured Specific sites on the body based on age, gender, and race Body density is calculated using specific equations Percent body fat calculated from body density Underwater Weighing : Underwater Weighing Fig 18.3 Body Fatness for Health and Fitness : Body Fatness for Health and Fitness Recommended body fat Males 10-20% Females 15-25% Health concerns Obesity Anorexia Obesity : Obesity More evidence points to as a risk factor for CHD, and directly tied to two of major risk factors Primary contributing factor: adult-onset diabetes, menstrual abnormalities, reproductive problems, heart size and function, arthritis, gout, and hypertension Secondary contributing factor: endometrial carcinoma Diseases correlated with atherosclerotic disease, gallbladder disease, and death Obesity : Obesity BMI of >30 as a classification of obesity Prevalence of obesity in U.S. adults increased 15% in 1976-80 23.3% in 1988-94 30.9% in 1999-2000 Include those classified as overweight (BMI 25-29) Prevalence of overweight & obesity is 64.5% Obesity : Obesity Prevalence of overweight in children and adolescents (ages 6-19) 5-7% in late 1970 11% in 1988-94 15% in 2000 Associated with an increase of type 2 diabetes ObesityFat Cell Size vs. Number : ObesityFat Cell Size vs. Number 25 billion fat cells in normal-weight individual 60-80 billion in obese individual During weight loss Fat cell size decreases, not fat cell number Severe obesity (fat mass >30 kg) Due to increase in fat cell number (hyperplasia) Less severe obesity Due to increase in fat cell size (hypertrophy) Hyperplasia Associated with greater difficulty losing weight and maintaining weight loss ObesityFat Cell Size and Number : ObesityFat Cell Size and Number Fig 18.4 Obesity Genetic and Cultural Factors : Obesity Genetic and Cultural Factors Genetic factors Account for about 25% of the transmissible variance for fat mass and percent body fat Cultural factors Account for about 30% Set Point Theory : Set Point Theory The tendency of a person to return to a certain weight suggests that there is a biological set point for body weight, much like the set points for any negative feedback biological control system Set Point and Obesity : Set Point and Obesity Physiological set point model Biological signals provide input to hypothalamus Food intake is either increased or decreased to maintain body weight Cognitive set point model Cognitive signals about perception of body weight Influences food intake to maintain body weight Physiological Set Point : Physiological Set Point Fig 18.5 Cognitive Set Point : Cognitive Set Point Fig 18.6 Nutrient Balance : Nutrient Balance Static energy balance Increase intake of 250 kcals•day-1 would lead to 14 pound weight gain over one year Nutrient Balance : Nutrient Balance Dynamic energy balance Increase in energy intake results in increased body weight Energy expenditure also increases and weight is maintained at a new, higher level Results in weight gain of only 3.5 pounds in a year Nutrient Balance : Nutrient Balance Carbohydrate and protein Excess intake is oxidized Body regulates expenditure to match intake Does not contribute to weight gain Fat Excess intake is not necessarily oxidized Fat expenditure depends on total energy expenditure Contributes to weight gain The Food Quotient : The Food Quotient Food quotient (FQ) Indicates the mix of CHO and fat in the meal 1.00 = 100% CHO 0.85 = 50% CHO, 50% fat 0.70 = 100% fat Respiratory quotient (RQ) Indicates the mix of CHO and fat oxidized Similar to FQ The FQ, RQ, and Nutrient Balance : The FQ, RQ, and Nutrient Balance RQ = FQ Nutrient balance RQ/FQ ratio = 1.0 RQ > FQ Not oxidizing as much fat as consumed RQ/FQ ratio > 1.0 RQ < FQ Using more fat than is consumed RQ/FQ ratio < 1.0 RQ/FQ Ratio : RQ/FQ Ratio Fig 18.7 Energy Expenditure and Weight Control : Energy Expenditure and Weight Control Diets high in fat are linked to obesity Fat grams contain twice as many calories as carbohydrates Nutrient balance can most easily be achieved with a low fat diet Calories count and must be considered! Basal Metabolic Rate (BMR) : Basal Metabolic Rate (BMR) Rate of energy expenditure under standardized conditions Supine position, immediately after rising, 12-18 hours following a meal Similar to resting metabolic rate (RMR) Represents 60-75% total energy expenditure Lower in women, declines with age Related to fat-free mass Reduced in response to reduced caloric intake (dieting or fasting) Exercise can maintain BMR Caloric Intake and BMR : Caloric Intake and BMR Fig 18.8 Thermogenesis : Thermogenesis “Heat generation” associated with: Ingestion of meals (thermic effect of feeding) Small part of total energy expenditure Not associated with obesity Brown adipose tissue “Futile cycles” Metabolic cycles (NA+/K+ pump activity) Physical Activity : Physical Activity Accounts for 5-40% total energy expenditure Depends on activity level Important in determining obesity Inverse relationship between physical activity and percent fat Relationship Between Physical Activity and Body Fatness : Relationship Between Physical Activity and Body Fatness Fig 18.9 Effect of Exercise on Appetite : Effect of Exercise on Appetite Most humans Energy intake is increased across a broad range of energy expenditure Maintains body weight Formerly sedentary individuals Net loss of appetite on an exercise program Facilitates weight loss Relationship of Exercise and Appetite : Relationship of Exercise and Appetite Fig 18.10 Body Weight and Caloric Intake vs. Occupational Activity : Body Weight and Caloric Intake vs. Occupational Activity Fig 18.11 Exercise and Body Composition : Exercise and Body Composition Individuals who exercise generally have lower body weight and percent fat Weight loss in conjunction with exercise Less lean body mass is lost More fat mass is lost Weight Loss vs.Weight Maintenance : Weight Loss vs.Weight Maintenance Weight loss Exercise contributes a small fraction to weight loss Weight maintenance Light to moderate exercise Fats make up a large fraction of energy expended Moderate exercise Expends large amounts of fat and calories Fitness and weight loss goals Vigorous exercise Effective in expending calories and achieving fitness and fat loss goals Diet, Exercise, and Weight Control : Diet, Exercise, and Weight Control Energy and nutrient balance is more easily achieved on a low fat diet Exercise increases the chance that energy balance will be achieved Exercise promotes health-related benefits Increased fitness, HDL cholesterol, fibrinolysis Chapter 18 Body Composition and Nutrition for Health : Chapter 18 Body Composition and Nutrition for Health

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