Body Composition Chapter 4

Objectives Define body composition and understand its relationship to assessment of recommended body weight. Explain the difference between essential fat and storage fat. Describe various techniques used to assess body composition.

Objectives Be able to assess body composition using skinfold thickness and girth measurements. Understand the importance of body mass index (BMI) and waist circumference in the assessment of risk for disease.

Objectives Be able to determine recommended weight according to recommended percent body fat values and BMI. Learn how to measure body composition. Assess your risks for potential disease.

Introduction Body composition Recommended body weight Fat component Percent body fat Nonfat component Lean body mass Recommended body weight Assessment of body composition

Essential and Storage Fat Total fat Essential fat Normal physiological function Locations Percent of total weight Storage fat Functions Location of storage

Typical Body Composition of an Adult Man and Woman

Techniques to Assess Body Composition Dual Energy X-ray Absorptiometry (DEXA) Research and medical facilities Measurements SEE ± 1.8 percent

Techniques to Assess Body Composition Hydrostatic weighing Most common technique Buoyancy of fat tissue Drawbacks SEE ± 0.5 percent

Techniques to Assess Body Composition Air displacement Bod Pod Air displaced by person inside the chamber Comparison to hydrostatic weighing SEE ± 2.2 percent

Techniques to Assess Body Composition Skinfold thickness Anthropometric measurements Relation of subcutaneous fat and total body fat SEE ± 3.5 percent Skinfold sites Hydration and physical activity

Techniques to Assess Body Composition Girth measurements Limitations SEE ± 4 percent Measurement locations Women: upper arm, hip, and wrist Men: waist and wrist

Body Fat Assessment According to Girth Measurements

Techniques to Assess Body Composition Bioelectrical impedance Accuracy is questionable 10 percentage points Measure of electrical resistance Fat tissue is less efficient conductor Factors that can affect results

Body Mass Index (BMI) Determine thinness and excessive fatness Height and weight to estimate fat values Calculations Most widely used measure to determine obesity and overweight Disease risk Lowest risk 22-25 range

Mortality Risk Versus Body Mass Index (BMI)

Body Mass Index (BMI) Compared with a BMI between 22-25: BMI greater than 25 Mortality rates Weakness of BMI Location on body fat Use with athletes

Disease Risk According to Body Mass Index (BMI)

Overweight & Obesity Trends in the U.S., 1960-2006

Waist Circumference Storage of fat affects disease risk Android obesity Apple shape Risks Fat around organs Gynoid obesity Pear shape Waist circumference measurements

Disease Risk from WC and BMI

Determining Recommended Body Weight Mortality Obesity vs. underweight Essential fat Lean tissue decreases with age Extra fat percentage for each decade of life Computing recommended body weight

Body Composition Classifications According to Percent Body Fat

Importance of Regular Body Composition Assessment Fat gain Weight gain per year Lean tissue lost per year Body composition reassessment

Visceral Fat Compared to SBC or RTP Fat for Disease Risk

Real Life Stories

Real Life Stories Critical Thinking Questions 1. Can you identify what got Camille started on her weight-loss program? Was the starting point self- or environmentally determined? Discuss the pros or cons that got her going on her weight-loss program. How was the end point of the weight loss determined? List the benefits of her long-term approach to weight loss. 2. What weight-loss programs are likely to end up being just another “yo-yo diet”? Have you had any experiences with some of these methods; and if so, what were the results? What strategies are more likely to lead to permanent and sustainable weight loss? 3. Discuss the roles of aerobic exercise and strength training on weight management. Do you think strength training is a good idea for those who are trying to lose weight? Is it as important for women as for men?