© mcgraw-hill higher education. all rights reserved. chapter 12 evaluating body composition

© McGraw-Hill Higher Education. All rights reserved.

Chapter 12Chapter 12

Evaluating Body CompositionEvaluating Body Composition


Chapter 12 OutlineChapter 12 OutlinePublic Health RisksPublic Health Risks

Sources of Adulthood ObesitySources of Adulthood Obesity

Anthropometric Assessments of Body Anthropometric Assessments of Body CompositionComposition

Evaluating Body Composition of AdultsEvaluating Body Composition of Adults

Screening Tool for Steroid Abuse - FFMIScreening Tool for Steroid Abuse - FFMI

Skinfold Assessments of Percent fat of Skinfold Assessments of Percent fat of Children and YouthChildren and Youth

Comparison of Body Composition MethodsComparison of Body Composition Methods


Definitions and StatisticsDefinitions and Statistics

Overweight: Body mass index (BMI) 25 - Overweight: Body mass index (BMI) 25 - 29.9 kg29.9 kg..mm-2-2

Obese: BMI Obese: BMI 30 kg 30 kg..mm-2-2

Percent Body Fat: Proportion of total Percent Body Fat: Proportion of total weight that is fat. weight that is fat. Proportion of Americans who are Proportion of Americans who are overweight and obese is growing.overweight and obese is growing.NHANES 1999-2002: 62% of women; NHANES 1999-2002: 62% of women; 69% of men were overweight.69% of men were overweight.


Public Health RisksPublic Health Risks

Overweight:Overweight:– increased risk of heart disease and stroke.increased risk of heart disease and stroke.– increased risk of breast cancer in post-increased risk of breast cancer in post-

menopausal.menopausal.

Body fat percent that is too low provides Body fat percent that is too low provides health risks.health risks.– Intelligent application of assessment and Intelligent application of assessment and

education about body fat can help people education about body fat can help people establish desirable, intelligent weight goals.establish desirable, intelligent weight goals.


Sources of Adulthood ObesitySources of Adulthood Obesity

Consume more calories than expend.Consume more calories than expend.Why some people gain weight while others Why some people gain weight while others do not?do not?– Genetic?Genetic?– Environmental?Environmental?– Psychological?Psychological?

Both parental obesity and being obese as Both parental obesity and being obese as a child and adolescent increase risk of a child and adolescent increase risk of adult obesity.adult obesity.


Laboratory Body Composition Laboratory Body Composition MeasuresMeasures

Underwater weighingUnderwater weighing

Bod PodBod Pod

Dual energy X-ray absorptiometry (DXA)Dual energy X-ray absorptiometry (DXA)


Underwater Weighing (Hydrostatic)Underwater Weighing (Hydrostatic)

Popular lab method to measure body Popular lab method to measure body composition.composition.

Objective is to measure body volume.Objective is to measure body volume.

Body Density: ratio of body weight and body Body Density: ratio of body weight and body volume.volume.Body Density = weight in air Body Density = weight in air body volume. body volume.

Percent fat is calculated from body density. Percent fat is calculated from body density.


Underwater Weighing (Hydrostatic)Underwater Weighing (Hydrostatic)

Based on Archimedes’ Principle:Based on Archimedes’ Principle:– when an object is submerged in water, when an object is submerged in water,

difference between weight in air and weight difference between weight in air and weight under water equals weight of the water under water equals weight of the water displaced.displaced.

Weight of water displaced divided by Weight of water displaced divided by density of water equals body volume.density of water equals body volume.


Steps to Determine Body Steps to Determine Body DensityDensity

Determine underwater weight.Determine underwater weight.

Determine land weight.Determine land weight.

Determine air in the body.Determine air in the body.– Residual lung volume must be measured.Residual lung volume must be measured.– Largest potential source of error in Largest potential source of error in

underwater weighing technique.underwater weighing technique.

Determine density of the water.Determine density of the water.– Based on temperature of water.Based on temperature of water.


Computing Body Volume (BV)Computing Body Volume (BV)

BV = [(Weight – Weight W)BV = [(Weight – Weight W) Dw] – air in body Dw] – air in body

where BV = Body Volume, Weight W = weight in where BV = Body Volume, Weight W = weight in water, Dw = density of water, air in body = water, Dw = density of water, air in body = residual volume + 100 ml.residual volume + 100 ml.


Computing Body DensityComputing Body Density

Body Density = Weight Body Density = Weight Body Volume Body Volume


BODPODBODPOD

Body plethysmograph or body box.Body plethysmograph or body box.

Based on Boyle’s Law:Based on Boyle’s Law:– Pressure of a gas varies inversely with its volume.Pressure of a gas varies inversely with its volume.

Air volume in the box can be measured.Air volume in the box can be measured.

When person enters box, pressure changes and When person enters box, pressure changes and can measure new volume in box.can measure new volume in box.

Very high correlation with underwater weighing.Very high correlation with underwater weighing.

Easier than underwater weighing for people Easier than underwater weighing for people uncomfortable in water.uncomfortable in water.


Converting Body Density to Converting Body Density to Percent FatPercent Fat

Variation in body density is due to air, fat Variation in body density is due to air, fat weight, and fat-free weight.weight, and fat-free weight.

Density of air = 0.Density of air = 0.

Density of fat weight ~ 0.90 g/cc.Density of fat weight ~ 0.90 g/cc.

Density of fat-free weight ranges from ~ Density of fat-free weight ranges from ~ 1.0 to 3.0 g/cc.1.0 to 3.0 g/cc.– mean assumed to be 1.10 g/ccmean assumed to be 1.10 g/cc


Two-component ModelsTwo-component ModelsMake an assumption that density of fat tissue is 0.90 g/ccMake an assumption that density of fat tissue is 0.90 g/ccMake assumption that density of fat-free tissue is a specific Make assumption that density of fat-free tissue is a specific value:value:– 1.10 g/cc 1.10 g/cc (Siri, Brozek), 1.113 g/cc (Schutte), 1.106 g/cc (Wagner, Ortiz)(Siri, Brozek), 1.113 g/cc (Schutte), 1.106 g/cc (Wagner, Ortiz)

Siri Percent Fat Equation:Siri Percent Fat Equation:– %fat = (495 %fat = (495 Body Density) – 450 Body Density) – 450

Brozek Percent Fat Equation:Brozek Percent Fat Equation:– %fat = (457 %fat = (457 Body Density) – 414 Body Density) – 414

Schutte Percent Fat Equation (for African American males):Schutte Percent Fat Equation (for African American males):– %fat = (437.4 %fat = (437.4 Body Density) – 392.8 Body Density) – 392.8

Wagner Percent Fat Equation (for African American males)Wagner Percent Fat Equation (for African American males)– %fat = (486 %fat = (486 Body Density) – 439 Body Density) – 439

Ortiz Percent Fat Equation (for African American females)Ortiz Percent Fat Equation (for African American females)– %fat = (485 %fat = (485 Body Density) - 439 Body Density) - 439


Four-component ModelsFour-component Models

Two-component model has limitations when Two-component model has limitations when measuring children, older adults, and some measuring children, older adults, and some non-white ethnic groups.non-white ethnic groups.– Total body water and bone mineral content may Total body water and bone mineral content may

vary from assumed values, which alter density vary from assumed values, which alter density of fat-free weight component.of fat-free weight component.

Four-component model includes water and Four-component model includes water and mineral content, along with body density.mineral content, along with body density.


Four-component Percent Fat ModelFour-component Percent Fat Model

%fat =%fat = (2.749 (2.749 Body Density) Body Density)

– – (0.727 * w) (0.727 * w)

– – (1.146 * m) (1.146 * m)

– – 2.0532.053

where w is water and m is mineral.where w is water and m is mineral.

Dual energy X-ray absorptiometry (DXA) Dual energy X-ray absorptiometry (DXA) technology can measure bone mineral content.technology can measure bone mineral content.


Comparison of Two- and Four-Comparison of Two- and Four-component Modelscomponent Models

Four-component model viewed as most Four-component model viewed as most accurate method.accurate method.

Differences in percent fat estimates Differences in percent fat estimates between two- and four-component models between two- and four-component models are not large.are not large.


DXADXAParticipant lies on a table and a total body scan is Participant lies on a table and a total body scan is conducted.conducted.Scan divides non-bone tissue into fat and lean Scan divides non-bone tissue into fat and lean components.components.– Total body bone mineral massTotal body bone mineral mass– Bone-free lean tissueBone-free lean tissue– Fat massFat mass

Fat-free mass = Fat-free mass = total body bone mineral mass + bone-free lean tissuetotal body bone mineral mass + bone-free lean tissue

Does not measure total body water.Does not measure total body water.Can assess regional body composition.Can assess regional body composition.


Anthropometric Assessment of Anthropometric Assessment of Body CompositionBody Composition

Body Mass Index (BMI)Body Mass Index (BMI)

Body CircumferencesBody Circumferences

Waist-Hip Ratio (WHR)Waist-Hip Ratio (WHR)

SkinfoldsSkinfolds


Body Mass Index (BMI)Body Mass Index (BMI)

BMI = weight (kg) BMI = weight (kg) height height22 (m) (m)– weight (kg) = pounds weight (kg) = pounds 2.2 2.2– height (m) = inches * 0.0254height (m) = inches * 0.0254– heightheight22 (m) = height (m) * height (m) (m) = height (m) * height (m)

Used in large-scale public health studies.Used in large-scale public health studies.


World Health Organization Criteria for World Health Organization Criteria for Overweight and Obesity by BMIOverweight and Obesity by BMI

CategoryCategory BMIBMI

UnderweightUnderweight < 18.5< 18.5

Normal WeightNormal Weight 18.5 – 24.918.5 – 24.9

OverweightOverweight 25.0 – 29.925.0 – 29.9

Obese Class IObese Class I 30.0 – 34.930.0 – 34.9

Obese Class IIObese Class II 35.0 – 39.935.0 – 39.9

Obese Class IIIObese Class III > 40> 40


Prediction of Percent Fat from BMIPrediction of Percent Fat from BMIGallagher et al. (1996)Gallagher et al. (1996)

%fat =%fat = (1.46 * BMI)(1.46 * BMI)

+ (0.14 * Age)+ (0.14 * Age)

- (11.61 * Gender)- (11.61 * Gender)

- 10.02- 10.02

where Male = 1 and Female = 0.where Male = 1 and Female = 0.

R = .81, SEE = 5.7%fat


Prediction of Percent Fat from BMIJackson et al. (2002)

%fat = (1.61 * BMI)

+ (0.13 * Age)

- (12.11 * Gender)

- 13.91

where Male = 1 and Female = 0.

R = .75, SEE = 5.5%fat


BMI StandardsBMI Standards

BMI BMI lacks accuracylacks accuracy when estimating %fat of when estimating %fat of individuals.individuals.Does not take into account the quality of Does not take into account the quality of weight (i.e., fat vs. lean).weight (i.e., fat vs. lean).A BMI of 25 or 30 kgA BMI of 25 or 30 kg..mm-2-2 does not correspond does not correspond to same percent fat at different ages.to same percent fat at different ages.BMI of 25 kgBMI of 25 kg..mm-2-2 is a percent fat of about 20% is a percent fat of about 20% for men and about 30% for women.for men and about 30% for women.BMI of 30 kgBMI of 30 kg..mm-2-2 is a percent fat of about 27% is a percent fat of about 27% for men and about 40% for women.for men and about 40% for women.


Body CircumferencesBody Circumferences

Circumferences most highly correlated with Circumferences most highly correlated with percent fat are in abdomen and hip.percent fat are in abdomen and hip.

Percent fat estimated by circumferences is Percent fat estimated by circumferences is used by U.S. Navy.used by U.S. Navy.



People with central obesity are at high risk for CVD.People with central obesity are at high risk for CVD.

Central obesity often assessed by waist-hip ratio.Central obesity often assessed by waist-hip ratio.

Waist circumference – at narrowest point between Waist circumference – at narrowest point between the umbilicus and xiphoid process.the umbilicus and xiphoid process.

Hip circumference – at largest circumference Hip circumference – at largest circumference around buttocks.around buttocks.

Combination of BMI and WHR can be used to Combination of BMI and WHR can be used to define health risk.define health risk.

WHR may be better measure of obesity than BMI.WHR may be better measure of obesity than BMI.– WHR more highly associated with heart attacks than BMIWHR more highly associated with heart attacks than BMI



As WHR increases, risk of heart attack As WHR increases, risk of heart attack increases.increases.

Significantly increased risk of heart attack:Significantly increased risk of heart attack:– For men, WHR > 0.90For men, WHR > 0.90– For women, WHR > 0.83For women, WHR > 0.83


Types of ObesityTypes of Obesity

Android Obesity – central or upper body Android Obesity – central or upper body adiposity (apple-shaped).adiposity (apple-shaped).– Increased WHR indicative of android obesityIncreased WHR indicative of android obesity– Android obesity = higher risk of heart attackAndroid obesity = higher risk of heart attack

Gynoid Obesity – excess fat deposited in Gynoid Obesity – excess fat deposited in hips and thighs (pear-shaped).hips and thighs (pear-shaped).– Gynoid obesity = lower risk of heart attackGynoid obesity = lower risk of heart attack


SkinfoldsSkinfolds

Highly correlated with body density from Highly correlated with body density from hydrostatic weighing.hydrostatic weighing.Double thickness of subcutaneous fat is Double thickness of subcutaneous fat is measured with calipers.measured with calipers.Need proper training to locate and measure Need proper training to locate and measure skinfolds.skinfolds.– Improper site selection main reason for errors.Improper site selection main reason for errors.

Measured on right side of body for Measured on right side of body for standardization.standardization.


Common Skinfold SitesCommon Skinfold Sites

ChestChestAxillaryAxillaryTricepsTricepsSubscapularSubscapularAbdomenAbdomenSuprailiumSuprailiumThighThighMedial CalfMedial Calf


Skinfold Measurement MethodsSkinfold Measurement Methods

Pinch and pull skin with left hand (use thumb Pinch and pull skin with left hand (use thumb and index finger) and hold caliper in right hand.and index finger) and hold caliper in right hand.Place caliper perpendicular to fold.Place caliper perpendicular to fold.Place caliper ~ 1 cm (0.25 in.) from fingers.Place caliper ~ 1 cm (0.25 in.) from fingers.Release caliper so full tension is exerted.Release caliper so full tension is exerted.Read dial to nearest 0.5 mm ~ 1 to 2 seconds Read dial to nearest 0.5 mm ~ 1 to 2 seconds after releasing grip.after releasing grip.Take minimum of 2 measures. If they vary by Take minimum of 2 measures. If they vary by more than 1 mm, take a third measure.more than 1 mm, take a third measure.


Skinfold Measurement MethodsSkinfold Measurement Methods

If consecutive pinches become smaller, If consecutive pinches become smaller, the fat is being compressed. Go on to the fat is being compressed. Go on to next site and return to trouble spot after next site and return to trouble spot after taking other measures.taking other measures.

Final value is average of two that best Final value is average of two that best represent skinfold site.represent skinfold site.

Typically, complete a measurement at one Typically, complete a measurement at one site before moving to another site.site before moving to another site.

Practice on 50 to 100 subjects.Practice on 50 to 100 subjects.


Skinfold Assessment ofSkinfold Assessment ofPercent Fat of AdultsPercent Fat of Adults

Generalized equations Generalized equations (Jackson-Pollock equations):(Jackson-Pollock equations):– Developed on large, heterogeneous samples (18 to 61 Developed on large, heterogeneous samples (18 to 61

years of age).years of age).– Separate equations are needed for men and women.Separate equations are needed for men and women.

Equation for sum of three skinfolds is typically Equation for sum of three skinfolds is typically used.used.– Men: chest, abdomen, thighMen: chest, abdomen, thigh– Women: triceps, suprailium, thighWomen: triceps, suprailium, thigh


Jackson-Pollock 3-Site Skinfold Jackson-Pollock 3-Site Skinfold EquationsEquations

Women:Women:

Body Density =Body Density = 1.0994211.099421

- (0.0009928 * - (0.0009928 * 3 skinfolds)3 skinfolds)

- (0.00000023 * - (0.00000023 * 3 3 skinfoldsskinfolds22))

- (0.0001382 * Age)- (0.0001382 * Age)R = .84, SEE = 3.9%fat

Siri, Brozek, Shutte, Wagner, or Ortiz equations can then be used to estimate percent fat.


Jackson-Pollock 3-Site Skinfold Equations

Men:

Body Density = 1.10938

- (0.0008267 * 3 skinfolds)

- (0.0000016 * 3 skinfolds2)

- (0.0002574 * Age)

R = .91, SEE = 3.5%fat

Siri, Brozek, Shutte, Wagner, or Ortiz equations can then be used to estimate percent fat.


Bioelectrical Impedance (BIA)Bioelectrical Impedance (BIA)Based on principle that resistance to flow of Based on principle that resistance to flow of electrical current through the body is related to electrical current through the body is related to total body water.total body water.With traditional method, electrodes are placed With traditional method, electrodes are placed on wrist and ankle.on wrist and ankle.Newer methods do not require electrodes.Newer methods do not require electrodes.


Bioelectrical Impedance (BIA)Bioelectrical Impedance (BIA)

Non-detectable (low level) electrical Non-detectable (low level) electrical current is transmitted through the body.current is transmitted through the body.

Resistance to flow of the current is Resistance to flow of the current is measured.measured.

Accuracy is similar to skinfolds, except for Accuracy is similar to skinfolds, except for obese and very lean people.obese and very lean people.

Accuracy of newer hand-to-hand and foot-Accuracy of newer hand-to-hand and foot-to-foot analyzers lower than for whole-to-foot analyzers lower than for whole-body BIA analyzers.body BIA analyzers.


Traditional BIA MeasurementTraditional BIA Measurement


BIA Assessment GuidelinesBIA Assessment Guidelines

No diuretic medications with a week of testNo diuretic medications with a week of test

Avoid alcohol within 2 days of testAvoid alcohol within 2 days of test

Avoid exercise within 12 hours of testAvoid exercise within 12 hours of test

Avoid eating or drinking within 4 hours of Avoid eating or drinking within 4 hours of testtest

Urinate within 30 minutes of testUrinate within 30 minutes of test


Evaluating Body Composition of Evaluating Body Composition of AdultsAdults

Relationship between weight and all-cause Relationship between weight and all-cause mortality is J-shaped.mortality is J-shaped.– Being seriously overweight increases risk of Being seriously overweight increases risk of

diseases.diseases.– Being too underweight can result in health Being too underweight can result in health

problems.problems.

Athletes generally have lower % fat than Athletes generally have lower % fat than general population.general population.


Standards for Evaluating Percent FatStandards for Evaluating Percent Fatfor Menfor Men

AgeAge

< 30< 30 30-3930-39 40-4940-49 >49>49

HighHigh > 28%> 28% > 29%> 29% > 30%> 30% > 31%> 31%

OptimalOptimal 11-21%11-21% 12-22%12-22% 13-23%13-23% 14-24%14-24%

Very LowVery Low 5% 5% 6% 6% 7% 7%

8% 8%


Standards for Evaluating Percent Fatfor Women

Age

< 30 30-39 40-49 >49

High > 32% > 33% > 34% >

35%

Optimal 15-25% 16-26% 17-27% 18-

28%

Very Low 11% 12% 13%

14%


Weight-reduction GoalsWeight-reduction Goals

Can determine sound weight reduction Can determine sound weight reduction goals if know percent fat and body weight.goals if know percent fat and body weight.

Based on calculation of fat weight and fat-Based on calculation of fat weight and fat-free weight, healthy weight is determined.free weight, healthy weight is determined.

Weight-reduction goal is determined from Weight-reduction goal is determined from estimated body weight for the healthy estimated body weight for the healthy percent body fat.percent body fat.


Healthy WeightHealthy Weight

1.1. Estimate percent fat.Estimate percent fat.

2.2. Fat weight = weight * (%fat Fat weight = weight * (%fat 100) 100)

3.3. Fat-free weight = weight – fat weightFat-free weight = weight – fat weight

4.4. Healthy weight = Healthy weight =

fat-free weight fat-free weight [1 – (Desired %fat [1 – (Desired %fat 100)] 100)]


Screening Tool for Steroid Abuse - Screening Tool for Steroid Abuse - FFMIFFMI

Fat-free Mass Index (FFMI)Fat-free Mass Index (FFMI)

FFMI = fat-free mass/(height)FFMI = fat-free mass/(height)22

– Fat-free mass is in kgFat-free mass is in kg– Height is in metersHeight is in meters

Normalized FFMI = Normalized FFMI = FFMI + [6.3 x (1.8 – height in meters)FFMI + [6.3 x (1.8 – height in meters)

A normalized FFMI > 25 is likely to A normalized FFMI > 25 is likely to indicate steroid abuseindicate steroid abuse


Skinfold Assessments of Percent fat Skinfold Assessments of Percent fat of Children and Youthof Children and Youth

Boys:Boys:

%fat = [0.735 * (Triceps + Calf)] + 1.0%fat = [0.735 * (Triceps + Calf)] + 1.0

Girls:Girls:

%fat = [0.610 * (Triceps + Calf)] + 5.0%fat = [0.610 * (Triceps + Calf)] + 5.0


Comparison of Body Composition Comparison of Body Composition MethodsMethods

Most accurate methods are DXA and Most accurate methods are DXA and laboratory assessed body density (Bod laboratory assessed body density (Bod Pod and underwater weighing).Pod and underwater weighing).

Skinfolds is recommended option for field Skinfolds is recommended option for field testing:testing:– Accurate and reproducible.Accurate and reproducible.– Simple and inexpensive.Simple and inexpensive.– EducationalEducational


Formative Evaluation ofFormative Evaluation ofChapter ObjectivesChapter Objectives

Identify the public health problems associated with body Identify the public health problems associated with body composition.composition.Identify the methods used to measure body composition Identify the methods used to measure body composition of youth and adults.of youth and adults.Identify the limitations of the two-component model for Identify the limitations of the two-component model for computing percent body fat when applied to children, computing percent body fat when applied to children, older adults, and members of various racial groups.older adults, and members of various racial groups.Calculate percent body fat of youths and adults from Calculate percent body fat of youths and adults from skinfold equations.skinfold equations.Be able to evaluate body composition of youth and Be able to evaluate body composition of youth and adults.adults.Calculate weight goals for selected levels of desired Calculate weight goals for selected levels of desired percent body fat.percent body fat.Evaluate the accuracy of the various methods used to Evaluate the accuracy of the various methods used to measure body composition.measure body composition.


Chapter 12Chapter 12

Evaluating Body CompositionEvaluating Body Composition

© mcgraw-hill higher education. all rights reserved. chapter 12 evaluating body composition

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