Chapter 6 Lecture

Understanding

Body Composition

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Learning Outcomes

• Discuss how body composition is related to lifelong fitness and wellness.

• Describe how the assessment of body size and shape differs from the assessment of body composition.

• Evaluate your BMI and body circumferences and relate your scores to your overall health status.

• Set and continually reevaluate goals to reach your healthy body fat percentage.

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Body Composition Concepts

Body Composition– The relative amounts of lean tissue and fat tissue in

your body

Lean Body Mass– Your body's total amount of lean/fat-free tissue

(muscles, bones, skin, organs, body fluids)

Fat Mass– Body mass made up of fat tissue

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Body Composition Concepts continued

Percent Body Fat– The percentage of your total weight that is fat tissue

(weight of fat divided by total body weight)

Essential Fat– Fat necessary for normal body functioning (including in

the brain, muscles, nerves, lungs, heart, and digestive and reproductive systems)

Storage Fat– Nonessential fat stored in tissue near the body's

surface

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Body Composition for Men and Women

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Why Do My Body Size, Shape, and Composition Matter?

Knowing body composition can help assess health risks.

– More people are now overweight or obese.– Estimates of body composition provide useful

information for determining disease risks.

Evaluating body size and shape can motivate healthy behavior change.

– Changes in body size and shape can be more useful measures of progress than body weight.

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How Can I Evaluate My Body Size and Shape?

Calculate your body mass index (BMI).– BMI: a common measurement to assess disease risks

Understand the limits of BMI:– Scores do not differentiate between fat and lean body

mass.

Measure your body circumference:– Use waist and hip measurements to determine your

waist-to-hip ratio (WHR).

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Estimating BMI

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BMI and Health

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Waist Circumference, BMI, and Disease Risk

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How to Evaluate Body Size and Shape continued

Identify your body's patterns of fat distribution.

Gynoid Pattern– "Apple" shaped– Excess body fat on upper body and trunk– Associated with greater disease risk

Android Pattern– "Pear" shaped– Excess fat mainly on lower body

(hips and thighs)

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Android and Gynoid Body Fat Distribution

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Assessing Body Composition

Skinfold Measurements– Use calipers to measure skinfold thickness– Accurate assessments require experience and practice

Dual-Energy X-Ray Absorptiometry (DXA)– The "gold standard" for assessing body composition– Uses low-radiation x-rays to distinguish body

components

Hydrostatic Weighing (Underwater Weighing)– Requires an equipped facility

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Assessing Body Composition continued

Air Displacement (Bod Pod)– Measures total body air displacement– Used with other measures for a full assessment

Bioelectrical Impedance Analysis (BIA)– Measures resistance of tissues to electrical currents– Accuracy depends on machine quality and participant

cooperation

Estimates from Circumferences or BMI– Provide rough estimates– Can provide a starting point for weight management

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A DXA Machine Uses Low-Radiation X-rays to Determine Body Composition

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Hydrostatic Weighing Uses Total Body Water Displacement to Calculate Estimated Body Fat

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The "Bod Pod" Uses Total Body Air Displacement to Calculate Body Fat

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Bioelectrical Impedance Analysis (BIA) Measures Resistance of Tissues to Electrical Currents

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How Can I Evaluate and Change My Body Composition?

• Determine if your percent body fat is within a healthy range.

• Set reasonable composition goals.

• Follow a well-designed exercise and nutrition plan.

• Regularly monitor your body size, shape, and composition.

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Percent Body Fat Norms for Men and Women

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Normal Weight Obesity

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

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

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

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Follow a Well-Designed Exercise and Nutrition Plan

Weekly:– Assess your body shape and size (use indicators

such as a mirror and the fit of your clothes).– Assess your weight.

Monthly or Every Few Months:– Measure your body's circumferences.– Measure your BMI.– Measure your percent body fat.