Chapter 6 Lecture

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BodyComposition

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Learning Objectives

• Define body composition• Explain the relationship between body fat

percentage and disease risk• Explain the concept of optimal body weight• Discuss the importance of assessing body

composition• Explain body composition assessment using

hydrostatic weighing, the skinfold test, body mass index, and waist-to-hip circumference ratio

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Body Composition

• The relative amounts of fat and fat-free tissues (bone, muscle, organs) in the body

• Expressed as percentage of fat in the body– Overweight

– body fat percentage above the recommended level

– Obesity– >25% body fat for men– >35% body fat for women

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Body Composition Relationship to Health

Essential Fat• Located in nerves and cell membranes• Necessary for body functioning• 3% for men• 12% for women

Storage Fat• Located in adipose tissue

• visceral (around organs) • subcutaneous (below the skin)

• 8–19% for men, recommended low end of 12–15% for young adult

• 21–32% for women, recommended low end of 21–25% for young adult

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Storage Fat

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Body Composition Relationship to Health

Android Pattern of Obesity• Fat is primarily stored in upper body and

around the waist• Most common in men• Greater risk of developing heart disease and

diabetes

Gynoid Pattern of Obesity• Fat is primarily stored in waist, hips, and

thighs• Most common in women

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Health Risks Associated with Levels of Body Fat

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Overweight and Obesity in the United States

• Current obesity estimates– 34% of adults– 17% of children/adolescents ( 2–19 yrs.)

• NIH estimates obesity directly contributes to 15–20% of deaths in United States

• Contributes significant effect on health care costs– 10% of all medical costs in United States– $147 billion per year direct medical costs– predicted to rise sharply in future

• WHO indicates U.S. obesity rates highest in world– in 2010 every state had 20% or higher obesity rate

– 36 states 25% or more– 12 states 30% or more

• Adult rates are leveling off• Childhood obesity rates show NO evidence of decreasing

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Obesity Rates in United States

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Creeping Obesity

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Chronic Conditions of Overweight and Obesity

• Heart disease (also called cardiovascular disease or CVD)

• Diabetes • Cancers (breast, prostate, colon)• Joint problems and osteoarthritis• Sleep apnea• Gallbladder disease• Menstrual abnormalities• Difficulty with conception and pregnancy

complications

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Benefits of a Healthy Weight

Mental Benefits• Better self-esteem & body image• More positive mindset• Less anxiety and depression

Physical Benefits• Lower risk of diabetes, cardiovascular

disease, and cancer• Easier motion for physical activity and

everyday living • Lower death rate

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Health Effects of Underweight

• Loss of muscle mass and strength resulting from malnutrition• Osteoporosis• Menstrual abnormalities that can lead to infertilitySevere underweight from eating disorders (anorexia nervosa and bulimia) can lead to• Heart problems• Digestive disorders• Kidney damage• Anemia• Lethargy• Muscle weakness• Dry skin• Compromised immune function

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Assessing Body Composition

Field Methods• Height/weight tables• Body mass index (BMI)• Skinfold test• Waist measurement & waist-to-hip ratio

Laboratory Measures• Dual energy X-ray absorptiometry (DXA)• Hydrostatic weighing • Air displacement• Bioelectrical impedance analysis (BIA)

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Skinfold Test

Exercise Video: Skinfold TestPLAYPLAY

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Waist-to-Hip Measurement

Exercise Video: Waist-to-Hip MeasurementPLAYPLAY

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Estimating BMI

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Relationship Between BMI and % BF

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ABC News: Normal-Weight Obesity

Discussion Questions

1. How can a person who is "normal" weight be at risk for obesity-related diseases?

2. What are health risks of women who are normal-weight obese?

3. In addition to increased percentage of body fat, what characteristic of body fat points to increased health risks?

PlayVideoPlayVideo

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Determining Ideal Body Weight

• Calculate % body fat and select a healthy body fat % range based on sex and age– Example: Male – age 25, weight 185 lb, 30% body fat,

body fat % range of 8–19% recommended• Step 1. Compute fat-free weight

– Total body weight – fat weight = fat-free weight– 100% – 30% body fat = 70% fat-free weight– 70% x 185 lb = 129.5 lb fat-free weight

• Step 2. Calculate optimal weight– Optimal weight = fat-free weight/(1 – optimal % fat)– 129.5/(1 – .08) = 140.8 lb optimal weight– 129.5/(1 – .19) = 159.9 lb optimal weight

• See Lab 6.2 worksheet to determine ideal body weight

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Weight Management

• Set goals• Get regular body fat assessments• Re-evaluate optimum weight over time• Guard against lean mass loss during weight loss• Incorporate regular aerobic and resistance

exercise• Eat a healthy diet

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Summary

• Body composition is the relative amounts of fat and fat free tissue in the body

• A high percentage of body fat is associated with increased risk for numerous diseases

• Body fat distribution also affects disease risks associated with overweight and obesity

• Common field techniques for estimating body fat include skinfold measurements, BMI assessment, and waist-to-hip ratio

• DXA is considered the gold standard measure for estimating body fat

• Get regular body composition assessments while trying to lose or gain weight