1. 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
Presentation revised and updated by
Brian B. Parr, Ph.D.
University of South Carolina Aiken

2. Nutritional Goals U.S. Dietary Goals (1977)
Increase carbohydrate intake to 55-60% total calories
Decrease fat intake to less than 30% total calories
Decreased saturated fat to less than 10% total calories
Increase polyunsaturated and monounsaturated fat to 10% of caloric intake
Decrease dietary cholesterol to 300 mg per day
Reduce sugar consumption to 15% total calories
Decrease salt intake to 3 grams per day

3. Nutritional Goals Institute of Medicine dietary recommendations (2002)
45–65% calories from carbohydrates
20–35% calories from fat
10–35% from protein
Infants and younger children need higher proportion of fat (25–40%)

4. Nutritional Goals Dietary Guidelines for Americans (2005)
Consume a variety of nutrient-dense foods and beverages within and among the basic food groups
Choose foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol
Maintain body weight in a health range
Balance calories from foods and beverages with calories expended
Engage in regular physical activity and reduce sedentary activities

5. 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 nearly all (97–98%) healthy persons
Adequate Intakes (AI)
Recommended daily intake based on apparently healthy people
Tolerable Upper Intake Level (UL)
The highest intake level that is likely to pose no risk
Estimated Average Requirement (EAR)
The intake estimated to meet requirements of half of healthy people

6. 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 2000 kcal•day-1 diet

7. Nutritional Labeling Food labels contain: Serving size information
Total calories and fat calories
Total fat grams, saturated fat grams, cholesterol, and the %DV for each
Based on a 2,000 calorie diet
Total carbohydrate and its sources
Percent of DV for vitamins and minerals
Sodium is given special attention

8. Example of a Food Label
Figure 18.1

9. Classes of Nutrients—Water
Absolutely essential for life
Loss of only 3-4% body water affects performance
Water loss
Normally ~2500 ml per day
Temperature and exercise can increase water loss to 6-7 liters per day
Water intake
Beverages (1500 ml)
Solid food (750 ml)
Metabolic processes (250 ml)
AI is 2.7 L/day (women), 3.7 L/day (men)

10. 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
B vitamins
Thiamin (B-1), riboflavin (B-2), niacin, pyroxidine (B-6), folic acid, B-12, pantothenic acid, biotin,
Involved in energy metabolism
Vitamin C
Maintenance of bone, cartilage, and connective tissue

11. 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

12. Classes of Nutrients—Minerals
Calcium
Important in teeth and bone structure
Osteoporosis
Iron
Component of hemoglobin
Anemia
Sodium
Associated with hypertension
In sodium-sensitive individuals

13. 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

14. 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

15. 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

16. Meeting the Guidelines and Achieving the Goals
The new Dietary Guidelines for Americans describes a healthy diet as one that:
Emphasizes fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products
Includes lean meats, poultry, fish, beans, eggs, and nuts
Is low in saturated fat, trans fat, cholesterol, salt (sodium), and added sugars

17. Food Group Plans MyPyramid (2005) Revision of 1992 Food Guide Pyramid
Includes major food groups
Grains, vegetables, fruits, milk, and meat & beans
How much of each category to meet 2000 kcal/day energy expenditure
Special attention on physical activity
Website provides individualized dietary plan
Based on age, gender, and level of physical activity

18. MyPyramid Food Groups
Table 18.3

19. Food Group Plans Dietary Approaches to Stop Hypertension (DASH)
Developed to prevent hypertension and lower blood pressure in those with hypertension
Healthy eating approach consistent with good health:
Reducing cardiovascular risk factors
Achieving and maintaining a healthy body weight

20. The DASH Eating Plan
Table 18.4

21. Methods of Assessing Overweight and Obesity
Metropolitan Life Insurance Company’s height/weight tables
Original 1959 tables and 1983 update
Relative weight (RW)
Person’s weight divided by midpoint of medium frame weight range
RW of 1.00 is considered normal
RW of 1.10 (10% above normal) is overweight
RW of 1.20 (20% above normal) is obese
Problems with height/weight tables
High RW could be due to excess fat or muscle

22. Methods of Assessing Overweight and Obesity
Body mass index (BMI)
Weight (kg) / height (m2)
Classification for adults
Underweight: BMI <18.5 kg/m2
Normal: BMI 18.5–24.9 kg/m2
Overweight: BMI 25.0–29.9 kg/m2
Obesity: BMI ≥30.0 kg/m2
No way to tell actual body composition
A very muscular person could be classified as obese

23. Methods of Measuring Body Composition
Isotope dilution
Measurement of total body water
Uses an isotope of water
Photon absorptiometry
Determines mineral content and density of bones
Potassium-40
Measurement of lean tissue
Hydrostatic (underwater) weighing
Determination of body density
Dual energy X-ray absorptiometry
Estimates lean tissue, bone, mineral, and fat

24. Methods of Measuring Body Composition
Near infrared interactance (NIR)
Uses an infrared light beam
Radiography
Measurement of fat width
Ultrasound
Measures thickness of subcutaneous fat
Nuclear Magnetic Resonance (NMR)
Volumes of specific tissues
Total body electrical conductivity (TOBEC)
Electrical conductivity of lean and fat tissue

25. Methods of Measuring Body Composition
Bioelectrical impedance analysis (BIA)
Measurement of total body water and fatness
Air displacement plethysmography
Measurement of body density
Skinfold thickness
Estimate of total body fatness

26. Body Composition Assessment
Four-component model
Mineral, water, protein, and fat
Best estimates of percent fat
Three-component model
Body water, protein + mineral, and fat
Body water + protein, mineral, and fat
Accounts for variations in bone density or body water
Two-compartment model
Fat mass and fat-free mass
Most commonly used method

27. Two-Component System of Body Composition
Body divided into fat-free and fat mass
Fat mass
Density = 0.900
Fat-free mass
Density = 1.100
Measurement of whole-body density
Underwater weighing
Skinfolds
Equation to convert body density to percent fat
Based on age, gender, and race
Siri equation:
% body fat =
495
Density
- 450

28. Underwater Weighing Density = mass / volume Measurement of body volume
Subject is submerged in tank of water
Weight of water displaced = loss of weight when submerged (Ma-Mw)
Weight of water displaced is divided by density of water (DW) to calculate volume of water displaced
Volume is corrected for residual lung volume (VR) and gas in intestinal tract (VGI)
D = M V
- VR - VGI MA
(MA-MW) =
(DW)

29. The Underwater Weighing Technique
Figure 18.2

30. Skinfolds
Prediction of body density from estimation of subcutaneous fat
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

31. Body Fatness for Health and Fitness
Recommended body fatness
Males
10-20%
Females
15-25%
Health concerns above and below these values
Obesity
Anorexia

32. Obesity Diseases linked to obesity: Hypertension Type 2 diabetes
Coronary heart disease (CHD)
Stroke
Gallbladder disease
Osteoarthritis
Sleep apnea and respiratory problems
Some cancers
Endometrial, breast, prostate, colon
Other health conditions

33. Obesity Prevalence of overweight and obesity in U.S. adults
30.6% are obese (BMI ≥30)
65.7% are overweight (BMI ≥25)
Includes those classified as obese
Higher in some ethnic groups
16.5% of U.S. children are overweight
Distribution of body fat is important
Higher risk of CVD with upper body obesity
Waist circumference >102 cm (men) and >88 cm (women)
Waist to hip ratio >0.95 (men) and >0.80 (women)

34. Fat Cell Size vs. Number and Obesity
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

35. Relationship Between Fat Cell Size and Fat Cell Number to Total Body Fat
Figure 18.3

36. Causes of Obesity Genetic factors Cultural factors
Account for about 25% of the transmissible variance for fat mass and percent body fat
Cultural factors
Account for about 30%

37. Set Point and Obesity Set point theory
Biological set point for body weight much like the set points for other physiological variables
Physiological set point model
Biological signals provide input to hypothalamus
Blood glucose, lipid stores, weight on feet
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

38. Physiological Set Point Model for Control of Body Weight
Figure 18.4

39. Cognitive Set Point for Control of Body Weight
Figure 18.5

40. Energy Balance Static energy balance
Increase intake of 250 kcals•day-1 would lead to 14 pound weight gain over one year
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
change of
energy stores
energy
intake
expenditure = -
rate of change
of energy stores
rate of change of
energy intake
energy expenditure = -

41. Nutrient Balance Carbohydrate and protein Fat
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

42. The Food Quotient Food quotient (FQ) Respiratory quotient (RQ)
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

43. 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

44. Relationship Between the RQ/FQ Ratio and Energy Balance
Figure 18.6

45. Diet 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!
Adherence to the diet is more important than the type of diet followed
Calories from foods and beverages should be balanced with calories expended
Gradually decrease caloric intake and increase physical activity

46. Physical Activity for Weight Control
To reduce the risk of chronic disease
30 minutes of moderate-intensity physical activity on most days of the week
To manage weight and prevent gradual weight gain
60 minutes of moderate- to vigorous-intensity activity on most days of the week
To sustain weight loss
60–90 minutes of moderate-intensity physical activity

47. Energy Expenditure and Weight Control
Basal metabolic rate (BMR)
Rate of energy expenditure under standardized conditions
Supine position, immediately after rising, 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

48. Decrease in Basal Metabolic Rate During Semi-Starvation
Figure 18.7

49. Energy Expenditure and Weight Control
Thermogenesis
“Heat generation”
Thermic effect of feeding
Increased energy expenditure following ingestion of meals
Small part of total energy expenditure
Not predictive of obesity
Brown adipose tissue
Increases heat production in response to norepinephrine and thyroid hormones
“Futile cycles”
Metabolic cycles (Na+/K+ pump activity)

50. Energy Expenditure and Weight Control
Physical activity and exercise
Includes exercise and occupational 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
Individuals accumulating more than 10,000 steps per day are more likely to be in “normal” BMI range

51. Relationship Between Body Fatness and Nonbasal Energy Expenditure
Figure 18.8

52. 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

53. Pattern of Caloric Intake for Rats Versus the Durations of Exercise
Figure 18.9

54. Pattern of Caloric Intake Versus Occupational Activity
Figure 18.10

55. 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

56. Exercise, Weight Loss, and Weight Maintenance
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

57. National Weight Control Registry
“Successful losers”
Average weight loss of 30 kg for 5.5 years
No evidence of psychological distress
Limited caloric intake to 1,400 kcal/day with 25% calories from fat
Expended 400 kcal/day through physical activity
Strategies for long-term weight loss
Engaging in high-level physical activity
Eating a diet low in calories and fat
Consistent eating plan, including breakfast
Self-monitoring weight regularly
Catching slips before they result in weight regain

58. Caloric Cost for Walking, Jogging, and Running
Table 18.8

59. Estimated Energy Expenditure During Exercise
Table 18.9

60. 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