fw190 body composition

Chapter

6

Copyright © 2017 McGraw-Hill Education. All rights reserved.

No reproduction or distribution without the prior written consent of McGraw-Hill Education. 1

Ahead:

What Is Body Composition,

and Why Is It Important?

Assessing Body Mass Index, Body

Composition, and Body Fat Distribution

Setting Body Composition Goals

Making Changes in Body Composition



The human body is

divided into fat-free

mass and body fat

Fat-free mass is the body’s

nonfat tissues

▪ Bone, water, muscle, connective

tissue, organ tissues, and teeth

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Essential fat: fats incorporated in various

tissues of the body, critical for normal body

functioning

Adipose tissue: tissue in which fat is stored;

fat cells

Subcutaneous fat: fat located under the skin

Visceral fat: fat located around major organs;

also called intra-abdominal fat



SOURCE: Adapted from Brooks, G. A., et al. 2005. Exercise

Physiology: Human Bioenergetics and Its Applications, 4th ed.

New York: McGraw-Hill; Santos, D.A., et al. 2014. Reference

Values for body composition and anthropometric measurements

in athletes. PLoS ONE 9(5): e97846.



Most important consideration: proportion of

body’s total weight that is fat

Percent body fat: percentage of total body weight

that is composed of fat

Overweight: body weight that falls above the

recommended range for good health

Sometimes defined as a body mass index between

25 and 29.9, a measure of the proportion of weight

to height



Obesity: severely overweight, characterized by

an excessive accumulation of body fat

May also be defined in terms

of some measure of total body

weight or a body mass index

of 30 or more

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Prevalence of obesity increased from 13% in

1960 to 27.7–34.9% today

62–69% of adult Americans are overweight

About 35.5% of men and 36.1% of women are

obese, according to the latest statistics

Obesity rates increased most among middle-aged

and older adults



Possible explanations:

More sedentary work and leisure activities

Fewer short trips on foot, and more by automobile

Fewer daily gym classes for students

More meals eaten outside the home

Greater consumption of fast food

Increased portion sizes

More soft drinks and convenience foods



Percentage Obese

Category 2008 2014 Difference (% points)

All adults 25.5 27.7 2.2

Ages 18-29 17.4 17.7 0.3

Ages 30-44 27.0 29.3 2.3

Ages 45-64 29.5 33.0 3.5

Ages 65 + 23.4 27.4 4.0

Women 23.9 26.7 2.8

Men 27.0 28.7 1.7

Whites 24.3 26.7 2.4

Hispanics 28.8 28.3 -0.5

Blacks 35.0 35.5 0.5

Annual income less than $36,000 30.0 32.3 2.3

Annual income $36,000-$89,999 25.8 27.7 1.9

Annual income $90,000 + 21.1 23.1 2.0

Midwest 26.8 29.7 2.9

South 26.9 29.2 2.3

East 24.7 26.6 1.9

West 22.8 24.6 1.8



Metabolic syndrome: cluster of symptoms

present in many overweight and obese people

that greatly increases their risk of heart disease,

diabetes, and other chronic illnesses

Symptoms include insulin resistance, abnormal

blood fats, abdominal fat deposition, type 2 diabetes,

high blood pressure, and high blood glucose



Conditions associated with metabolic

syndrome:

Chronic inflammation: a response of blood vessels

to such harmful substances as germs, damaged

cells, or irritants; can lead to heart disease, cancer,

allergies, and muscle degeneration

Fatty liver: increased fat storage in the liver; can

lead to liver inflammation and failure



Distribution of body fat is an important indicator

of health

Apple shape versus pear shape

Abdominal fat may be more easily mobilized and

sent into the bloodstream, increasing disease-related

blood fat levels

Waist circumference helps assess risks of unhealthy

body fat distribution



Too much body fat makes physical activity

difficult

Overfat people are less fit than others and lack

the muscular strength, endurance, and flexibility

that make normal activity easy



Being perceived as fat can be a source of

ridicule and ostracism, and can contribute to

psychological problems

Popular image of the “ideal” body has changed

greatly in the past 50 years



Overweight is associated with a substantial

increase in the risk of type 2 diabetes

Diabetes interferes with insulin production;

causes buildup of glucose in the blood

Types of diabetes

Type 1

Type 2

Gestational

Prediabetes

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Diabetes treatment

No cure

Managed through diet, exercise, medication

Diabetes prevention

90% of type 2 diabetes cases could be prevented by

lifestyle changes



Warning signs and testing for diabetes

Frequent urination; extreme hunger and thirst,

unexplained weight loss; extreme fatigue; blurred

vision; frequent infections; cuts and bruises that are

slow to heal; tingling and numbness in the hands or

feet; generalized itching with no rash

Screening involves a fasting blood test to check

glucose levels



Health experts generally view too little body fat

as a threat to health

Too little for women: less than 8–12%

▪ Amenorrhea: absent or infrequent menstruation, sometimes

related to low levels of body fat and excessive quantity or

intensity of exercise

Too little for men: less than 3–5%



Female athlete triad: condition consisting of

three interrelated disorders

Abnormal eating patterns (and excessive exercising)

A lack of menstrual periods (amenorrhea)

Decreased bone density

(premature osteoporosis)

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Some methods based on body fat; others on

total body weight

Assessments can provide information about

health risks and help establish reasonable

goals



Body mass index (BMI): measure of relative

body weight correlating highly with more direct

measures of body fat Calculated by dividing total body weight (in

kilograms) by the square of body height (in meters)

BMI between 18.5 and 24.9 is considered healthy



Body Mass Index (BMI) Classifications

WEIGHT STATUS CLASSIFICATION BODY MASS INDEX

Underweight <18.5

Severe thinness <16.0

Moderate thinness 16.0-16.9

Mild thinness 17.0-18.4

Normal 18.5-24.9

Overweight 25.0-29.9

Obese, Class I 30.0-34.9

Obese, Class II 35.0-39.9

Obese, Class III ≥40.0

Waist Circumference Classifications

WAIST CIRCUMFERENCE IN INCHES

(CENTIMETERS)

WAIST CIRCUMFERENCE IN

INCHES (CENTIMETERS)

RISK CLASSIFICATION WOMEN MEN

Normal <32 in. (80 cm) <37 in. (94 cm)

Increased ≥32 in. (80 cm) ≥37 in. (94 cm)

Substantially increased ≥35 in. (88 cm) ≥40 in. (102 cm)

SOURCE: Adapted from World Health Organization. 2008. Waist Circumference and Waist-to-Hip Ratio. Report of a WHO

Expert Consultation. Geneva: WHO.



Underwater weighing

Individual submerged and weighed under water

Percentage of fat and fat-free

weight calculated from body density

The Bod Pod

Small chamber containing

computerized sensors

measures body composition

by air displacement

BOD POD® Body Composition Tracking

System photo provided courtesy of

COSMED USA, Inc.



Skinfold measurements

Measures thickness of skinfolds

at different places on the body

Caliper: pressure-sensitive

measuring instrument with two

jaws that can be adjusted to

determine thickness of the skinfold

Important to test exact sites, to measure several

different times, and to take measurements at

approximately the same time of day

© Julie Brown / Custom Medical Stock

Photo



Bioelectrical impedance analysis (BIA)

Works by sending a small electrical current through

the body and measuring the body’s resistance to it

Advanced techniques: DEXA and TOBEC

DEXA works by measuring tissue absorption of

high- and low-energy X-ray beams

TOBEC estimates lean body mass by passing a

body through a magnetic field



WOMEN

Body Fat

Classification

20-39

YEARS

40-59

YEARS

60-79

YEARS

Essential* 8-12 8-12 8-12

Low/athletic** 13-20 13-22 13-23

Recommended 21-32 23-33 24-35

Overfat†

33-38 34-39 36-41

Obese†

≥39 ≥40 ≥42

MEN

Body Fat

Classification

20-39

YEARS

40-59

YEARS

60-79

YEARS

Essential* 3-5 3-5 3-5

Low/athletic** 6-7 6-10 6-12

Recommended 8-19 11-21 13-24

Overfat†

20-24 22-27 25-29

Obese†

≥25 ≥28 ≥30

NOTE: The cutoffs for recommended, overfat, and obese ranges in this table are based on a study that linked body mass index

classifications from the National Institutes of Health with predicted percent body fat (measured using dual-energy X-ray

absorptiometry).

*Essential body fat is necessary for the basic functioning of the body.

**Percent body fat in the low/athletic range may be appropriate for some people as long as it is not the result of illness or disordered

eating habits.

†Health risks increase as percent body fat exceeds the recommended range.

SOURCES: Gallagher, D., et al. 2009. Healthy percentage body fat ranges: An approach for developing guidelines based on body mass index. American

Journal of Clinical Nutrition 72: 694-701; Swain, D. P. 2013. ACSM's Resource Manual for Guidelines for Exercise Testing and Prescription, 7th ed.

Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health.

28Copyright © 2017 McGraw-Hill Education. All rights reserved.

No reproduction or distribution without the prior written consent of McGraw-Hill Education.

Waist circumference measurement and

waist-to-hip ratio calculations are the easiest

to perform

Total waist measurement of more than

40 inches for men and 35 inches for women

and a waist-to-hip ratio above 0.94 for young

men and 0.82 for young women are associated

with increased risk of heart disease and

diabetes



Endomorphs are round and pear shaped, with

wide hips and shoulders

Mesomorphs are lean and muscular and

respond well to exercise

Ectomorphs are thin and linear, with narrow

hips and shoulders



If assessment tests indicate that fat loss would

be beneficial, the first step is to establish a

realistic goal

Be sure your goal is realistic and will ensure

good health

© Lebazele/Getty Images RF



If you are overfat or have known risk factors,

consult a physician to determine a body

composition goal for your individual risk profile

Decide whether the body weight the formulas

suggest is realistic, meets your goals, is healthy,

and is reasonable to maintain



Focus on lifestyle

Track progress

Reassess your

body composition

occasionally during

the program

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