energy balance and body composition chapter 8. chapter 8 objectives describe energy balance and the...

Energy Balance Energy Balance and Body and Body

CompositionComposition

Chapter 8Chapter 8

Chapter 8 ObjectivesChapter 8 Objectives

• Describe energy balance and the consequences of not being in balance. • Discuss some of the physical, emotional, and environmental influences on food intake. • List the components of energy expenditure and factors that might influence each.

• Explain the basal metabolic rate and the factors that affect it.

• Discuss the role of physical activity in balancing the energy budget.

• Use equations and tables to determine energy requirements.

• Distinguish between body weight and body composition, including methods to assess each. • Define healthy body weight.

• Explain the methods used to assess body composition, including BMI and waist circumference.

• Identify relationships between body weight and chronic diseases. • Identify the health risks for underweight.

• Discuss the health risks for overweight, including heart disease, diabetes, and cancer.

• Compare and contrast the diagnoses, characteristics, and treatments of the different eating disorders.

• Identify eating disorders in the athlete including the female athlete triad and disordered eating.

• Discuss the characteristics and the treatment of the eating disorders anorexia nervosa and bulimia nervosa.

Energy BalanceEnergy Balance

• Excess energy is stored as fat• Healthy-weight person’s fat stores = 50,000

to 200,000 kcalories!

• Energy balance: energy in = energy out• A shift in balance causes weight changes

• Not simply fat changes

• 1 pound of fat = 3500 kcalories

Energy In: Food IntakeEnergy In: Food Intake

• Hunger• Physiological response to nerve signals and

chemical messengers• Hypothalamus

• Influences

• Satiation – stop eating• Satiety – not to start eating again

Hunger, Satiation, and SatietyHunger, Satiation, and Satiety


• Overriding hunger and satiety• Boredom, anxiety, stress

• External cues• Time of day, availability, sight, taste of food

• Environmental influences• Cognitive influences• Disordered eating


• Sustaining satiation and satiety• Nutrient composition

• Protein is most satiating

• Low-energy density

• High-fiber foods

• High-fat foods – strong satiety signals


• The hypothalamus• Control center for eating• Integrates messages

• Energy intake, expenditure, storage

• Gastrointestinal hormones

Energy OutEnergy Out

• Components of Energy Expenditure:1. Basal Metabolism

2. Physical Activity

3. Thermic Effect of Food (TEF)

4. Adaptive Thermogenesis

Energy Out: Basal MetabolismEnergy Out: Basal Metabolism

• About 2/3 of energy expended in a day• Metabolic activities

• All basic processes of life• Basal metabolic rate (BMR)

• Variations

• Weight

• Lean tissue

• Resting metabolic rate (RMR)

Factors that Affect the BMRFactors that Affect the BMR

Energy Out: Physical ActivityEnergy Out: Physical Activity

• Voluntary movement of skeletal muscles• Most variable component of energy

expenditure• Amount of energy needed

• Muscle mass• Body weight• Activity

• Frequency, intensity, and duration

Energy Out: Thermic Effect of Energy Out: Thermic Effect of FoodFood

• Acceleration of GI tract functioning in response to food presence• Releases heat

• Approximately 10 percent of energy intake• High-protein foods vs. high-fat foods• Meal consumption time frame

Energy Out: Adaptive Energy Out: Adaptive ThermogenesisThermogenesis

• Adapt to dramatically changing circumstances• Examples

• Extra work done by body• Amount expended is extremely variable• Not included in energy requirement

calculations

Components of Energy Expenditure

Estimating Energy Estimating Energy RequirementsRequirements

• Gender• BMR

• Growth• Groups with

adjusted energy requirements

• Age• Changes with age

• Physical activity• Levels of intensity

for each gender

• Body composition & body size• Height

• Weight

Body Weight and Body Body Weight and Body CompositionComposition

• Body weight = fat + lean tissue (incl water)Body weight = fat + lean tissue (incl water)• Ideal Body Weight: Fashion vs Health

• Not appearance based• Perceived body image and actual body size

• Damaging behaviors

• Subjective• Little in common with health

Defining Healthy Body WeightDefining Healthy Body Weight

• Body mass index• Relative weight for height

• BMI = weight (kg)

height (m)2

• Health-related classifications• Healthy weight: BMI = 18.5 to 24.9

• Underweight, overweight, obese

• Not a measure of body composition • Overweight vs overfat

Body Mass Index (BMI)

BMI and Body ShapesBMI and Body Shapes

Distribution of Body Weights Distribution of Body Weights in US Adultsin US Adults

Body Fat and Its DistributionBody Fat and Its Distribution

• Important information for disease risk• How much of weight is fat?• Where is fat located?

• Ideal amount of body fat depends on person

Body Fat Percentage and Body Body Fat Percentage and Body ShapesShapes


• Needing less body fat• Needing more body fat• Fat distribution

• Visceral fat• Central obesity

• Subcutaneous fat

““AppleApple”” and and ““PearPear”” Body Body Shapes ComparedShapes Compared


• Waist circumference • Indicator of fat distribution & central obesity

• Women: greater than 35 inches

• Men: greater than 40 inches

• Waist-to-hip ratio

• Other techniques for body composition• More precise measures

Common Methods Used to Common Methods Used to Assess Body FatAssess Body Fat

Health Risks Associated with Health Risks Associated with Body Weight & Body FatBody Weight & Body Fat

• Body weight and fat distribution correlate with disease risk and life expectancy• Correlations are not causes

• Risks associated with being underweight• Fighting against wasting diseases• Menstrual irregularities and infertility• Osteoporosis and bone fractures

BMI and MortalityBMI and Mortality


• Body weight and fat distribution correlate with disease risk and life expectancy• Correlations are not causes

• Risks associated with being underweight• Fighting against wasting diseases• Menstrual irregularities and infertility• Osteoporosis and bone fractures


• Risks associated with being overweight• Obesity is a designated disease

• Health risks

• More likely to be disabled in later years• Costs

• Money

• Lives

• Yo-yo dieting


• Cardiovascular disease• Elevated blood cholesterol & hypertension• Central obesity

• Diabetes – type II• Central obesity• Weight gains and body weight

• Cancer• Relationship is not fully understood


• Inflammation & metabolic syndrome• Change in body’s metabolism

• Cluster of symptoms

• Fat accumulation• Inflammation

• Elevated blood lipids• Promote inflammation

• Fit and fat versus sedentary and slim

Eating DisordersEating Disorders

Highlight 8Highlight 8

Eating DisordersEating Disorders

• Three disorders and prevalence

• Causes• Sociological, psychological, neurochemical

• Athletes are among most likely

Disorder Women Men

Anorexia Nervosa 0.9% 0.3%

Bulimia Nervosa 1.5% 0.5%

Binge Eating Disorder 3.5% 2%

Female Athlete TriadFemale Athlete Triad

• Disordered eating• Unsuitable weight standards

• Body composition differences

• Risk factors for eating disorders in athletes

• Amenorrhea• 2-5% vs 66%

• Osteoporosis • Stress fractures

Female Athlete TriadFemale Athlete Triad

Other Dangerous Practices of Other Dangerous Practices of AthletesAthletes

• Muscle dysmorphia• High-protein diets, supplements, weight train

for hours, abuse steroids• Similar to other distorted body images

• Food deprivation and dehydration practices• Impair physical performance

• Reduce muscle strength

• Decrease anaerobic power

• Reduce endurance capacity

Anorexia NervosaAnorexia Nervosa

• Distorted body image, denial, need for control• Protein-energy malnutrition (PEM)

• Similar to marasmus

• Impacts brain function and judgment

• Causes lethargy, confusion, and delirium

• Growth ceases, normal development falters

• Changes in heart size and strength

• Loss brain tissue, impaired immune response, anemia, GI tract deterioration

Anorexia NervosaAnorexia Nervosa

• Treatment• Multidisciplinary approach

• Food and weight issues

• Relationship issues

• After recovery• Energy intakes and eating behaviors may not

return to normal

• High mortality rate among psychiatric disorders

Bulimia NervosaBulimia Nervosa

• Distinct, more prevalent than anorexia• Secretive, not as physically apparent

• Close to ideal weight

• Single white female, well-educated• Binge-purge cycle: lack of control

• Binge for emotional comfort• Cannot stop, done in secret

• Purge• Shame and guilt

Bulimia NervosaBulimia Nervosa

• Physical consequences of binge-purge cycle• Compromised immune system, fluid/electrolyte

imbalances• Tooth erosion, red eyes, calloused hands

• Awareness of abnormality• Clinical depression and substance abuse rates

are high• Treatment

• Learn to eat three meals a day plus snacks• Interdisciplinary team

Binge-Eating DisorderBinge-Eating Disorder

• Periodic binging• Compared to bulimia nervosa

• Typically no purging, less restrictive dieting• Emotional side is similar

• Health risks greater than those of obese people who do not binge

• Behavioral disorder responsive to treatment

Eating Disorders in SocietyEating Disorders in Society

• Society plays central role in eating disorders• Known only in developed nations• More prevalent as wealth increases

• Food becomes plentiful

• Body dissatisfaction• Characteristics of disordered eating

energy balance and body composition chapter 8. chapter 8 objectives describe energy balance and the...

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