body composition

© 2011 McGraw-Hill Higher Education. All rights reserved.© 2011 McGraw-Hill Higher Education. All rights reserved.

Body CompositionBody Composition

Chapter SixChapter Six


What Is Body Composition?What Is Body Composition?

Body compositionBody composition is the body’s relative amounts is the body’s relative amounts of fat mass and fat-free massof fat mass and fat-free mass

Body fat includes two categories:Body fat includes two categories:– Essential fatEssential fat is crucial for normal body is crucial for normal body

functioningfunctioning3–5% of total body weight in males3–5% of total body weight in males

8–12% of total body weight in females8–12% of total body weight in females– The percentage is higher in women due to fat The percentage is higher in women due to fat

deposits in the breasts, uterus, and other sex-deposits in the breasts, uterus, and other sex-specific sites.specific sites.

– Most fat is storage in fat cells under the skin or Most fat is storage in fat cells under the skin or adipose tissueadipose tissue (subcutaneous fat) and around (subcutaneous fat) and around major organs (visceral or intra-abdominal fat)major organs (visceral or intra-abdominal fat)

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Body Composition of a Typical Man Body Composition of a Typical Man and Woman (20-24 Years Old)and Woman (20-24 Years Old)

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Defining Overweight and ObesityDefining Overweight and Obesity

OverweightOverweight is defined as total body weight is defined as total body weight above the recommended range for good above the recommended range for good health; ranges are set by population scaleshealth; ranges are set by population scales

ObesityObesity is defined as a more serious is defined as a more serious degree of overweight, characterized by degree of overweight, characterized by excessive accumulation of body fat.excessive accumulation of body fat.

The prevalence of obesity has increased The prevalence of obesity has increased from about 13% in 1960 to about 34% from about 13% in 1960 to about 34% todaytoday

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Excess Body Fat and WellnessExcess Body Fat and WellnessAs rates of overweight and obesity increase, so do the As rates of overweight and obesity increase, so do the problems associated with themproblems associated with themObesity reduces life expectancy by 10-12 yearsObesity reduces life expectancy by 10-12 yearsScientists believe that the average American life Scientists believe that the average American life expectancy will soon decline by 5 yearsexpectancy will soon decline by 5 yearsExcess body fat and wellness:Excess body fat and wellness:

Metabolic syndrome, diabetesMetabolic syndrome, diabetesBody fat distribution and healthBody fat distribution and health

– Performance of Physical ActivityPerformance of Physical Activity– Emotional Wellness and Self-ImageEmotional Wellness and Self-Image

Problems associated with very low levels of body fatProblems associated with very low levels of body fat– Less than 8-12% for women and 3-5% for menLess than 8-12% for women and 3-5% for men– Amenorrhea and loss of bone massAmenorrhea and loss of bone mass

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Body Fat DistributionBody Fat Distribution

Distribution of body fat is an important Distribution of body fat is an important indicator of healthindicator of healthThere are two recognizable shapesThere are two recognizable shapes

Apple (fat stored in the abdominal region)Apple (fat stored in the abdominal region)Pear (fat stored in the hips, thighs, buttocks)Pear (fat stored in the hips, thighs, buttocks)

Excessive fat in the abdominal region Excessive fat in the abdominal region increases the risk of many diseases such as:increases the risk of many diseases such as:

DiabetesDiabetesHeart diseaseHeart diseaseStrokeStrokeCertain cancersCertain cancersEarly mortalityEarly mortality

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Problems Associated with Very Low Problems Associated with Very Low Levels of Body FatLevels of Body Fat

Though not considered as prevalent a problem as Though not considered as prevalent a problem as obesity, too little body fat is also dangerousobesity, too little body fat is also dangerousExtreme leanness is linked to the following Extreme leanness is linked to the following disorders:disorders:

ReproductiveReproductiveCirculatoryCirculatoryImmune systemImmune system

Eating disorders have been associated with low Eating disorders have been associated with low percentages of body fat, especially in womenpercentages of body fat, especially in women

See the box “The Female Athlete Triad”77


Calculating Body Mass IndexCalculating Body Mass Index

Body Mass Index (BMI) is a measure that can Body Mass Index (BMI) is a measure that can classify risks, based on the concept that a classify risks, based on the concept that a person’s weight should be proportional to person’s weight should be proportional to heightheight

To determine this, body weight in kilograms is To determine this, body weight in kilograms is divided by the square of height in meters divided by the square of height in meters

Elevated BMI is linked to increased risk of Elevated BMI is linked to increased risk of disease, especially if associated with a large disease, especially if associated with a large waist circumferencewaist circumference

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Body Mass Index ClassificationsBody Mass Index Classifications

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Assessing Body Fat DistributionAssessing Body Fat Distribution

Two of the simplest forms to assess body Two of the simplest forms to assess body fat distribution are:fat distribution are:– Waist circumferenceWaist circumference– Waist-to-hip ratiosWaist-to-hip ratios

Disease risk increases with total waist measurement Disease risk increases with total waist measurement of more thanof more than

– 40 inches for men40 inches for men– 35 inches for women35 inches for women

Disease risk increases with total waist-to-hip Disease risk increases with total waist-to-hip measurement abovemeasurement above

– 0.94 for young men0.94 for young men– 0.82 for young women0.82 for young women

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Waist Circumference ClassificationWaist Circumference Classification

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Estimating Percent Body FatEstimating Percent Body Fat

There are many indirect methods that can provide There are many indirect methods that can provide an estimate of percent body fatan estimate of percent body fat

Techniques include:Techniques include:Underwater weighingUnderwater weighingSkinfold caliper measurementsSkinfold caliper measurementsBod PodBod PodBioelectrical Impedance Analysis (BIA)Bioelectrical Impedance Analysis (BIA)DEXA (Dual energy X-ray absorptiometry)DEXA (Dual energy X-ray absorptiometry)TOBEC (Total body electrical conductivity)TOBEC (Total body electrical conductivity)

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Percentage of Body Fat as the Criterion Percentage of Body Fat as the Criterion for Obesityfor Obesity

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Setting Body Composition Setting Body Composition GoalsGoals

If fat loss would benefit your health, set a If fat loss would benefit your health, set a realistic goal in terms of percent body fat or realistic goal in terms of percent body fat or BMIBMIIf you have underlying health issues, check If you have underlying health issues, check with your physician before setting a goalwith your physician before setting a goalUse the ratings in Table 6.1 or Table 6.2 to Use the ratings in Table 6.1 or Table 6.2 to choose a target value for BMI or percent body choose a target value for BMI or percent body fat.fat.A little weight loss at a time can be very A little weight loss at a time can be very beneficial; focus on a healthy lifestyle beneficial; focus on a healthy lifestyle including proper diet and exerciseincluding proper diet and exercise

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Making Changes in Body Making Changes in Body CompositionComposition

Lifestyle should be your focusLifestyle should be your focus

Include the following as part of a regular Include the following as part of a regular program:program:

Regular physical activityRegular physical activity

Endurance exerciseEndurance exercise

Strength trainingStrength training

Moderate energy intakeModerate energy intake

Reassess your body composition occasionally Reassess your body composition occasionally during your programduring your program

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BODY COMPOSITIONBODY COMPOSITIONChapter SixChapter Six

body composition

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