Body Composition and Nutrition for Health

Body Composition and Nutrition for Health

Objectives Identify the U.S. Dietary Goals relative to (a) carbohydrates and fats as a percent of energy intake, (b) salt and cholesterol, and (c) saturated and unsaturated fats. Contrast the Dietary Goals with the Dietary Guidelines. Describe what is meant by the terms Recommended Dietary Allowance (RDA) and Dietary Reference Intakes (DRIs), and how they relate to the Daily Value (DV) used in food labeling. List the classes of nutrients.

Objectives Identify the fat- and water-soluble vitamins, describe what toxicity is, and identify which class of vitamins is more likely to cause this problem. Contrast major minerals with trace minerals, and describe the role of calcium, iron, and sodium in health and disease. Identify the primary role of carbohydrates, two major classes, and the recommended changes in the American diet to improve health status. Identify the primary role of fat and the recommended changes in the American diet to improve health status.

Objectives List the food groups represented in the MyPyramid eating plan. Describe the Dietary Approaches to Stop Hypertension (DASH) eating plan, and describe similarities to the MyPyramid plan. Describe the limitation of the height/weight table in determining overweight and obesity.

Objectives 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 electrical conductivity, bioelectrical impedance analysis, air displacement plethysmography, and skinfold thickness. Describe the two-component model 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.

Objectives Explain the principle underlying the measurement of whole-body density with underwater weighing, and why one must correct for residual volume. Explain why there is an error of ±2.0% in the calculation of percent body fat with the underwater weighing technique. Explain how a sum of skinfolds can be used to estimate a percent body fatness value. 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.

Objectives Discuss the reasons why the average weight at any height (fatness) has increased while deaths from cardiovascular diseases have decreased. Distinguish between obesity due to hyperplasia of fat cells and that due to hypertrophy of fat cells. Describe the roles of genetics and environment in the development of obesity. Explain the set point theory of obesity, and give an example of a physiological and behavioral control system. Describe the pattern of change in body weight and caloric intake over the adult years.

Objectives Discuss the changes in body composition when weight is lost by diet alone versus diet plus exercise. Describe the relationship of the fat-free mass and caloric intake to the BMR. Define thermogenesis and explain how it is affected by both short- and long-term overfeeding. Describe the effect of exercise on appetite and body composition. Explain quantitatively why small differences in energy expenditure and dietary intake are important in weight gain over the years.

Outline Nutritional Goals Body Composition Obesity and Weight Control
Standards of Nutrition Classes of Nutrients Water Vitamins Minerals Carbohydrates Fats Protein Meeting the Guidelines and Achieving the Goals Food Group Plans Evaluating the Diet Body Composition Methods of Assessing Overweight and Obesity Methods of Measuring Body Composition Two-Component System of Body Composition Body Fatness for Health and Fitness Obesity and Weight Control Obesity Diet, Exercise, and Weight Control Energy and Nutrient Balance Diet and Weight Control Energy Expenditure and Weight Control

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

Meeting the U.S. Dietary Goals
Nutritional Goals Meeting the U.S. Dietary Goals Increase intake of fruits, vegetables, and whole grains Increase consumption of poultry and fish Decrease intake of meat Decrease intake of foods high in fat Substitute polyunsaturated fat for saturated fat Substitute nonfat milk for whole milk Decrease consumption of butter, fat, eggs, and other high-cholesterol foods Decrease consumption of sugar and foods high in sugar Decrease consumption of salt and foods high in salt

Dietary Guidelines for Americans (1980)
Nutritional Goals Dietary Guidelines for Americans (1980) Did not provide specific quantities to achieve for fat, cholesterol, salt, and carbohydrates More general statements for good health

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

Dietary Guidelines for Americans (2005)
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

Clinical Applications 18.1 Institute of Medicine Report
Nutritional Goals Clinical Applications 18.1 Institute of Medicine Report Established RDA for carbohydrate 130 g/day (meets glucose needs of brain) AI (adequate intake) for fiber set 38 g/day (men) and 25 g/day (women) AI for linoleic acid (omega-6 fatty acid) 17 g/day (men) and 12 g/day (women) AI for -linolenic acid (omega-3 fatty acid) 1.6 g/day (men) and 1.1 g/day (women) Maintained adult protein requirement 0.8 g/kg body weight/day AI for water set 3.7 L/day (men) and 2.7 L/day (women)

Nutritional Goals In Summary Current recommendations for the distribution of calories in foods include a broad range, rather than a single goal: carbohydrates: 45% to 65%, fats: 20% to 35%, and proteins: 10% to 35%. The publication, Dietary Guidelines for Americans, has been revised over time to reflect new science and to deal with nutrition (and physical activity) and health-related issues. The 2005 edition provides recommendations to meet the new nutritional standards with special focus on achieving energy balance.

Dietary Reference Intakes (DRIs)
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

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

Nutritional Labeling Food labels contain: Serving size information
Standards of Nutrition 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

Example of a Food Label Figure 18.1

In Summary The Recommended Dietary Allowance (RDA) is the quantity of a nutrient that will meet the needs of almost all healthy persons. The Daily Value (DV) is a standard used in nutritional labeling.

Water Absolutely essential for life
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)

Vitamins Fat-soluble vitamins A, D, E, K Can be stored in the body
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, and biotin Involved in energy metabolism Vitamin C Maintenance of bone, cartilage, and connective tissue

Summary of the Fat-Soluble Vitamins
Classes of Nutrients Summary of the Fat-Soluble Vitamins

Summary of the Water-Soluble Vitamins
Classes of Nutrients Summary of the Water-Soluble Vitamins

Classes of Nutrients In Summary The fat-soluble vitamins include A, D, E, and K. These can be stored in the body in large quantities, and a toxicity can develop. The water-soluble vitamins include thiamin, riboflavin, niacin, B6, folic acid, B12, pantothenic acid, biotin, and C. Most of these are involved in energy metabolism. Vitamin C is involved in the maintenance of bone, cartilage, and connective tissue.

Classes of Nutrients—Minerals
For a summary of minerals, see Table 18.2 Major minerals Calcium Sodium Phosphorus Magnesium Sulfur Potassium Chloride Trace elements Iron Iodine Fluoride Zinc Selenium Copper Cobalt Chromium Manganese Molybdenum Arsenic Nickel Vanadium

Minerals Calcium Important in teeth and bone structure Iron
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

Classes of Nutrients In Summary The major minerals include calcium, phosphorus, magnesium, sulfur, sodium, potassium, and chloride. The trace elements include iron, iodine, fluoride, zinc, selenium, copper, cobalt, chromium, manganese, molybdenum, arsenic, nickel, and vanadium. Inadequate calcium and iron intake have been linked with osteoporosis and anemia, respectively. Those with a genetic predisposition for hypertension due to sodium retention benefit from a reduction in salt intake.

Carbohydrates Sugars and starches Contain 4 kcal/g Major energy source
Classes of Nutrients Carbohydrates Sugars and starches Contain 4 kcal/g Major energy source Crucial for red blood cells and neurons Recommendations Choose or prepare foods and beverages with little added sugars or caloric sweeteners Reduce the incidence of dental caries by consuming sugar-containing foods and beverages less frequently

Carbohydrates Dietary fiber Non-digestible carbohydrates and lignin
Classes of Nutrients Carbohydrates Dietary fiber Non-digestible carbohydrates and lignin Reduces transit time in intestine Soluble fiber linked to lower serum cholesterol Functional fiber Non-digestible carbohydrates Have beneficial physiological functions Recommendations AI: 38 g/day for men, 25 g/day for women Increase dietary fiber and complex carbohydrate intake Decrease simple sugar intake

Classes of Nutrients Clinical Applications 18.2 Glycemic Index—What Is It and Is It Important? Glycemic index (GI) Blood glucose response (over 2 hours) to carbohydrate food Low GI foods make blood glucose regulation less challenging Glycemic load (GL) Takes into account amount of food eaten Can be used to plan meals Improved metabolic control in diabetics Reduce cholesterol and vascular inflammation Simplicity complicated by protein and fat in diet

Fats Important energy source Contain 9 kcals•gram–1 Triglycerides
Classes of Nutrients Fats Important energy source Contain 9 kcals•gram–1 Triglycerides Phospholipids Cholesterol Low-density lipoproteins (LDLs) Directly related to cardiovascular disease risk Increased by diets high in saturated fat High-density lipoproteins (HDLs) Protect against heart disease

Classes of Nutrients Fats Recommendations Consume less than 10% calories from saturated fats and less than 300 mg/day cholesterol Keep total fat intake between 20–35% calories Most fats should come from polyunsaturated and monounsaturated fats Choose and prepare meat, poultry, dry beans, milk, and milk products that are lean, low fat, or fat free Limit intake of fat and oils high in saturated and/or trans fatty acids

Clinical Applications 18.3 Diet Composition and Syndrome X
Classes of Nutrients Clinical Applications 18.3 Diet Composition and Syndrome X Clustering of risk factors associated with cardiovascular disease risk Hyperinsulinemia, hyperlipidemia, hypertension, and obesity Diet composition may be a contributing factor A high-fat, refined sugar (HFS) diet associated with: Insulin resistance in elevated plasma insulin Elevated triglycerides Larger fat cell size Higher blood pressure Compared to low-fat, complex-carbohydrate diet

Proteins Not a major source of energy 4 kcals•gram–1
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

Classes of Nutrients In Summary Carbohydrate is a primary source of energy in the American diet and is divided into two classes: that which can be metabolized (sugars and starches) and dietary fiber. Two recommendations to improve health status in the American population are to consume complex carbohydrates to represent about 45% to 65% of the calories, and to add more dietary fiber.

Classes of Nutrients In Summary Americans consume too much saturated fat, and the recommended change is to reduce this to no more than 10% of the total calories. Trans fat intake should be reduced as much as possible, and most fat intake should come from sources containing polyunsaturated and monounsaturated fatty acids. The protein requirement of 0.8 g/kg can be met with low-fat selections to minimize fat intake.

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

Food Group Plans Basic Four Food Group Plan Meat and meat substitutes
Meeting the Guidelines and Achieving the Goals Food Group Plans Basic Four Food Group Plan Meat and meat substitutes Milk and milk products Fruits and vegetables Grains (breads and cereals) Foods should have a high nutrient density Nutrient content in 1,000 kcal of a food

MyPyramid (2005) Revision of 1992 Food Guide Pyramid
Meeting the Guidelines and Achieving the Goals MyPyramid (2005) Revision of 1992 Food Guide Pyramid Includes major food groups Grains, vegetables, fruits, milk, and meat & beans How much of each category needed 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 Consistent with most dietary recommendations Should help control health conditions Vitamin E and potassium intake may be too low

MyPyramid Food Groups

Dietary Approaches to Stop Hypertension (DASH)
Meeting the Guidelines and Achieving the Goals Dietary Approaches to Stop Hypertension (DASH) Developed to prevent hypertension and to 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

The DASH Eating Plan

Evaluating the Diet How well is someone achieving the guidelines?
Meeting the Guidelines and Achieving the Goals Evaluating the Diet How well is someone achieving the guidelines? 24-hour recall method Remember what you ate the previous 24 hours Food records Person records what they eat Recommended to use 3–4 days in a week

In Summary The 2005 Dietary Guidelines for Americans identified two approaches to use to meet dietary standards and achieve a healthy body weight: The U.S. Department of Agriculture’s MyPyramid promotes a personalized approach to healthy eating and physical activity. It replaced the Food Guide Pyramid. The Dietary Approaches to Stop Hypertension (DASH) food plan is suitable for all to use in planning a healthy diet, whether one has hypertension or not.

Methods of Assessing Overweight and Obesity
Body Composition Methods of Assessing Overweight and Obesity Metropolitan Life Insurance height and weight tables No longer widely used 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

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 (DEXA) Estimates lean tissue, bone, mineral, and fat

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

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

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-component model Fat mass and fat-free mass Most commonly used method

Body Composition In Summary The BMI uses a simple ratio of weight-to-height squared (kg/m2) to classify individuals as being normal weight, overweight, or obese. However, just like the old height-weight tables, the BMI does not consider the composition of the body weight (i.e., proportion of muscle tissue vs. fat tissue). Body composition can be measured in terms of total body water (isotope dilution, bioelectric impedance analysis), bone density (photon absorptiometry), lean tissue mass (potassium-40), density (underwater weighing, air displacement plethysmography), and thickness of various tissues (ultrasound, radiography, skinfolds).

Body Composition In Summary Body composition assessment can be based on four-component (mineral, water, protein, and fat), three-component (body water, protein+mineral, and fat, or body water+protein, mineral, and fat), or two-component (fat-free mass and fat mass) models. The four-component model is the most accurate.

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

Estimating % Fat from Body Density
Body Composition Estimating % Fat from Body Density

Underwater Weighing Density = mass / volume Measurement of body volume
Body Composition 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)

The Underwater Weighing Technique
Body Composition The Underwater Weighing Technique Figure 18.2

Body Composition In Summary In the two-component system of body composition analysis, the body is divided into fat-free and fat mass, with densities of and 0.900, respectively. The estimate of the density of the fat-free mass must account for the differences that exist in various populations (i.e., children and African Americans).

Body Composition In Summary Body density is equal to mass ÷ volume. Underwater weighing is used to determine body volume using the principle of Archimedes: When an object is placed in water, it is buoyed up by a counterforce equal to the water it displaces. One can measure the actual volume of the water displaced, or the loss of weight while underwater. The weight of water is divided by the density of water to yield body volume, which must then be corrected for the residual volume and the volume of gas in the GI tract. The percent body fat value has an error of about ±2.0% due to the normal biological variation of the fat-free mass.

Body Composition 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 equations Generalized or specific equations Percent body fat calculated from body density Using Siri equation

Prediction of % Fat Based on Skinfolds
Body Composition Prediction of % Fat Based on Skinfolds

Body Fatness for Health and Fitness
Body Composition Body Fatness for Health and Fitness Recommended body fatness Males 10–20% Females 15–25% Health concerns above and below these values Obesity Anorexia nervosa and bulimia nervosa Calculation of optimal weight Optimal weight = Fat-free weight (1 – optimal % fat)

Body Composition In Summary Subcutaneous fat can be “sampled” as skinfold thicknesses, and a sum of skinfolds can be converted to a percent body fat with formulas derived from the relationship of the sum of skinfolds to a body composition standard based on a two-, three-, or four-component models. The recommended body fatness for males is 10% to 20%, and for females is 15% to 25%. There is concern about obesity and anorexia for those above and below these values, respectively.

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

Obesity Prevalence of overweight and obesity in U.S. adults (2004)
32.2% are obese (BMI ≥30) 66.3% 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 abdominal obesity Waist circumference >102 cm (men) and >88 cm (women) Waist to hip ratio >0.95 (men) and >0.80 (women)

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

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

Causes of Obesity Genetic factors
Account for about 25% of the transmissible variance for fat mass and percent body fat Affects components of energy expenditure Amount of spontaneous physical activity Resting metabolic rate Thermic effect of food Relative rate of carbohydrate and fat oxidation Cultural factors Account for about 30%

Obesity In Summary Obesity is associated with an increased mortality from cardiovascular disease and some types of cancer, but being overweight is not. Emphasis should be on maintaining or reducing weight in the overweight individual to decrease the chance of migration to the obese category. Obesity associated with fat mass in excess of 30 kg is due primarily to an increase in fat cell number, with fat cell hypertrophy being related to smaller degrees of obesity. Those with hyperplasia have a more difficult time losing weight and keeping it off. Genetic factors account for about 25% of the transmissible variance for fat mass and percent body fat; culture accounts to 30%.

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

Physiological Set Point Model for Control of Body Weight
Obesity Physiological Set Point Model for Control of Body Weight Figure 18.4

Cognitive Set Point for Control of Body Weight
Obesity Cognitive Set Point for Control of Body Weight Figure 18.5

Clinical Applications 18.4 Drugs, Dietary Supplements, and Weight Loss
Obesity Clinical Applications 18.4 Drugs, Dietary Supplements, and Weight Loss Little evidence that dietary supplements work Drugs, if they work, may have side effects Fen-phen promoted weight loss but caused: Pulmonary hypertension Heart valve abnormalities Electrocardiographic abnormalities Key points Focus of weight loss programs should be long-term diet and exercise behaviors Most drugs are for short-term use only If all the diet books, pills, and supplements worked, obesity would not be a problem

Obesity In Summary Investigators have proposed a set-point theory to explain obesity given the tendency for people who diet to return to their former weight. Theories based on weight sensors (ponderostatic), the blood glucose concentration (glucostatic), and the mass of lipid (lipostatic) have been proposed. A behavioral set-point theory has been proposed that relies on the person making appropriate activity and dietary judgments when body weight, size, or shape does not match up with that person’s ideal.

Energy Balance Static energy balance
Diet, Exercise, and Weight Control 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 = –

Diet, Exercise, and Weight Control
In Summary The dynamic energy balance equation correctly expresses the dynamic nature of changes in energy intake and body weight. An increase in energy intake leads to an increase in body weight; in turn, energy expenditure increases to eventually match the higher energy intake. Body weight is now stable at a new and higher value.

Nutrient Balance Carbohydrate and protein Excess intake is oxidized
Diet, Exercise, and Weight Control 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 Food quotient (FQ)
Diet, Exercise, and Weight Control 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
Diet, Exercise, and Weight Control 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

Relationship Between the RQ/FQ Ratio and Energy Balance
Diet, Exercise, and Weight Control Relationship Between the RQ/FQ Ratio and Energy Balance Figure 18.6

In Summary Nutrient balance exists for both protein and carbohydrate. Excess intake is oxidized and is not converted to fat.

Diet and Weight Control
Diet, Exercise, and Weight Control 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

Physical Activity for Weight Control
Diet, Exercise, and Weight Control 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

In Summary Diets with a high fat-to-carbohydrate ratio are linked to obesity. Nutrient balance for fat can be most easily achieved with a low-fat diet (high FQ). Calories do count, and they must be considered in any diet aimed at achieving or maintaining a weight loss goal.

Energy Expenditure and Weight Control
Diet, Exercise, and Weight Control Energy Expenditure and Weight Control 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

Decrease in Basal Metabolic Rate During Semi-Starvation
Diet, Exercise, and Weight Control Decrease in Basal Metabolic Rate During Semi-Starvation Figure 18.7

In Summary The BMR represents the largest fraction of total energy expenditure in sedentary persons. The BMR decreases with age, and women have lower BMR values than men. The fat-free mass is related to both the gender difference and to the decline in BMR with age. A reduction in caloric intake by dieting or fasting can reduce the BMR, while physical activity is important in maintaining it.

Diet, Exercise, and Weight Control 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 (10–15%) Not predictive of obesity Brown adipose tissue Increases heat production in response to norepinephrine and thyroid hormones Energy wasteful systems or futile cycles Metabolic cycles (Na+/K+ pump activity)

In Summary Thermogenesis (heat generation) is associated with the ingestion of meals (thermic effect of feeding), brown adipose tissue, and “futile cycles.” The thermic effect of food represents a small part of total energy expenditure and is not predictive of obesity.

Diet, Exercise, and Weight Control 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

Relationship Between Body Fatness and Nonbasal Energy Expenditure
Diet, Exercise, and Weight Control Relationship Between Body Fatness and Nonbasal Energy Expenditure Figure 18.8

Clinical Applications 18.5 A Calorie Is a Calorie
Diet, Exercise, and Weight Control Clinical Applications 18.5 A Calorie Is a Calorie In most studies, diet results in more weight loss than exercise Is a calorie of exercise equal to a calorie of diet restriction? Study by Ross, et al. Deficit of 700 kcal/day Through exercise or diet Both treatments lost 16.5 lbs—exactly what was predicted Exercise group lost more fat and preserved muscle Similar results in another study Equal caloric deficit through diet alone vs. diet plus exercise

Pattern of Caloric Intake for Rats Versus the Durations of Exercise
Diet, Exercise, and Weight Control Pattern of Caloric Intake for Rats Versus the Durations of Exercise Figure 18.9

Effect of Exercise on Appetite
Diet, Exercise, and Weight Control 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

Pattern of Caloric Intake Versus Occupational Activity
Diet, Exercise, and Weight Control Pattern of Caloric Intake Versus Occupational Activity Figure 18.10

Exercise and Body Composition
Diet, Exercise, and Weight Control 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 In general, those doing the largest amount of physical activity had the largest changes in percent body fat

In Summary Humans increase appetite over a broad range of energy expenditure to maintain body weight; however, formerly sedentary individuals show a net loss of appetite when they undertake an exercise program. When weight loss occurs with an exercise and diet program, less lean body mass is lost than when the same weight loss is achieved by diet alone.

Exercise, Weight Loss, and Weight Maintenance
Diet, Exercise, and Weight Control Exercise, Weight Loss, and 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

Clinical Applications 18.6 Successful Losers—How Much Exercise Is Needed to Keep the Weight Off? To maintain weight and prevent weight gain 60 min per day of moderate-intensity exercise To sustain weight loss: 60–90 min/day of moderate-intensity exercise 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

Clinical Applications 18.6 Successful Losers—How Much Exercise is Needed to Keep the Weight Off? Strategies for long-term weight loss (NWCR) 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

In Summary Moderate-intensity exercise is an appropriate choice for most Americans to achieve health-related and weight-loss goals. Plasma free fatty acids make up a large fraction of the energy supply for that level of physical activity. Moderate exercise promotes the expenditure of large amounts of fat and calories, consistent with achieving weight-loss and fitness goals. Vigorous activity is effective in expending calories and achieving fitness, performance, and fat-loss goals.

Caloric Cost for Walking, Jogging, and Running
Diet, Exercise, and Weight Control Caloric Cost for Walking, Jogging, and Running

Estimated Energy Expenditure During Exercise
Diet, Exercise, and Weight Control Estimated Energy Expenditure During Exercise

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

In Summary Participation in regular physical activity achieves a wide variety of health-related goals (e.g., increased cardiorespiratory fitness, HDL cholesterol, and fibrinolysis), and increases the chance that energy balance will be achieved.

Study Questions Summarize the range of carbohydrate, fat, and protein intakes recommended by the Institute of Medicine. What is the difference between an RDA standard and a Daily Value? Is there any risk in taking fat-soluble vitamins in large quantities? Explain. Which two minerals are believed to be inadequate in women’s diets? Relative to coronary heart disease, why is there a major focus on dietary fat? Generate a one-week menu using the MyPyramid website. How do the choices compare to those in the DASH eating plan?

Study Questions Using a height/weight table, how fat is a football player who is 74 inches tall and weighs 235 lb? Identify and describe the following methods of measuring body composition: isotope dilution, potassium-40, ultrasound, bioelectric impedance analysis, dual energy x-ray absorptiometry, skinfold thickness, and underwater weighing. Contrast the four-component and two-component models of body composition assessment. What is the principle of underwater weighing? Why should a different body density equation be used for children, in contrast to adults? Given: a twenty-year-old college male, 180 lb, 28% fat. What is his target body weight to achieve 17% fat?

Study Questions In terms of the resistance to weight reduction, contrast obesity due to hypertrophy with obesity due to hyperplasia of fat cells. Is obesity more related to genetics or the environment? If a person consumes 120 kcal per day in excess of need, what weight gain does the static energy balance equation predict compared to the dynamic energy balance equation? What does nutrient balance mean and how is the ratio of the RQ to FQ used to determine nutrient balance? Contrast a physiological set point with a behavioral set point related to obesity. What happens to the BMR when a person goes on a low-calorie diet?

Study Questions What recommendations would you give about the use of diet alone versus a combination of diet and exercise? What is thermogenesis and how might it be related to weight gain? What is the effect of exercise on appetite and body composition? What exercise recommendation is appropriate and consistent with achieving caloric-expenditure and fat-loss goals for someone who is sedentary and overweight?

Body Composition and Nutrition for Health

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Body Composition and Nutrition for Health

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Presentation on theme: "Body Composition and Nutrition for Health"— Presentation transcript:

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