Body Composition
We All Change in Many Ways
Genetics and Body Composition
Why is knowledge of body
composition so important?
 Health and Disease
 Performance
 Appearance
 Longevity
What Is Body Composition?
• Body Composition:
–The body’s relative amounts of fat mass
and fat-free mass (bone, water, muscle,
connective and organ tissues, teeth)
• Essential Fat:
–Crucial for normal body functioning
• Nonessential Fat:
–Adipose tissue
Typical Body Composition
Chapter 6
6
Essential Fat
 Fat stored in major organs, muscles, and
central nervous system
 Important for childbearing and hormonerelated functions
 Required for normal physiological
functioning
 Reducing essential fat below minimal amounts
can impair overall health.
 Extremes in dieting (and exercise) can reduce
essential fat stores.
Sex Differences in Essential Fat
Women
Men
8-12% of TBW
3-5% of Total
Body
Weight
Of this amount, 5 to
9% is called sexspecific, reserve
storage fat
contained in breast
and genital regions,
lower body
subcutaneous fat,
and intramuscular
depots
Stored Fat
Storage fat
accumulates mainly
in adipose tissues.
This fat includes
visceral fatty tissues
and adipose tissue
The common anatomic
deposited beneath
sites for subcutaneous
the skin’s surface
fat include the triceps, called subcutaneous
subscapula, iliac, midfat
abdomen, and upper
thigh
Distribution of Adipose Tissue
Chapter 6
10
Fat Mass versus Lean Body Mass
(LBM)
• Fat Mass:
–Actual fat mass in the body
• Lean Body Mass:
–Also called fat free mass (FFM), is the
total amount of nonfat (lean) parts of the
body.
–Composed of muscle, bone, organs,
and water
–73% water, 20% protein, 6% minerals,
and 1% ash.
Fat Mass and Lean Body Mass (LBM)
Calculations
• Fat Mass = Body fat % x scale weight
• Lean Body Mass (LBM) = Scale weight – fat
mass
• For example:
– 40-year-old female client weighs 130
pounds and has a body fat percentage of
28%
– Fat mass = .28 x 130 = 36 pounds of fat
– Lean body mass = 130 – 36 = 94 pounds
of lean body mass
How Lean is Too Lean?
• Males
– Lower limit of leanness equals about
3% body fat.
– Average body fat for men 18-24: 13-16%
• Females
– Lowest values for body fat correspond
to the essential fat content (about 12%).
– Average body fat for women 18-24: 2025%
Health Consequences of “Thinness”
• Too little body fat is associated with
reproductive, circulatory, and immune
system disorders
–Less than 10–12% for women
–Less than 5% for men
• Men
–Infertility
–Depression
Health Consequences of “Thinness”
• Women
• Ammenorrhea (completion cessation of
menses) occurs in 2 to 5% of women of
reproductive age, and 40% of female athletic
groups such as dancers, skaters, cheerleaders,
gymnasts, cross-country runners
• Oligomenorrhea (irregular menstrual cycles) or
amenorrhea increases the risk of bone loss and
musculoskeletal injury in premenopausal
women
Overweight and Obesity
• The most important consideration in
evaluating body weight and composition is
percent body fat (the proportion of total
body weight that is fat)
• Overweight:
– Total body weight above a recommended
range for good health
• Obesity:
– Severely overweight and overfat;
characterized by excessive accumulation of
body fat
Excess Body Fat and Wellness
• Increased risk of chronic disease and premature
death; associated health problems include:
– Unhealthy blood fat levels
– Impaired heart function
– Heart disease and hypertension
– Cancer
– Impaired immune function
– Gallbladder disease
– Kidney disease
– Skin problems
– Sleeping problems
Body Fat Distribution and Chronic
Disease
• Location of fat is important to health
–People who gain weight in the
abdominal area (apples) have an
increased risk of coronary heart
disease, high blood pressure,
diabetes, and stroke
–People who gain weight in the hip
area (pears) are at lower risk for
developing heart disease
Body Composition and Wellness
• Excess body fat decreases the ability to
perform physical activities
• Unrealistic expectations about body
composition can hurt self-image; exercise
improves body image
• Set a realistic goal and maintain a
wellness lifestyle to develop a healthy
body composition
Body Composition Tests
•
•
•
•
•
•
Body Mass Index (BMI)
Skinfold Measurement
Waist to Hip Ratio
Hydrostatic Weighing
Bioelectric Impedance
Dual-Energy X-Ray Absorptiometry
(DEXA)
• Bod Pod
Body Mass Index
• An assessment based on the concept that a
person’s weight should be proportional to height
• Elevated BMI is linked to increased risk of disease,
especially if associated with large waist
circumference
• Body Mass Index
– (weight in pounds/height in inches squared) x
703
• Overweight is defined as a BMI of 25 to 29.9
• BMI can be inaccurate
– Muscular individuals would have high BMI
levels, incorrectly being labeling as obese.
Skinfold Measurements
• Folds of skin are measured with a caliper.
• The measurements are used in equations that link
the thickness of skinfolds to percent body fat
calculations.
– Three to 9 different standard anatomical sites
around the body.
– The right side is usually only measured.
(Page 268
in NSCA)
Chapter 6
Waist to Hip Ratio
• Waist girth divided by the hip girth in
cm or inches
• This measure is often used to
determine the coronary artery disease
risk factor associated with obesity.
• Waist to hip ratio should be below:
• 0.85 to .90 for males
• 0.75 to .80 for females
Hydrostatic Weighing
• An individual is
submerged and
weighed under
water.
• Percentages of fat
and fat-free weight
are calculated from
body density.
Chapter 6
25
Bioelectric Impedance
• An electrical current is sent through the body, and the
resistance of the body to it is recorded. The resulting
estimates of how much water is in the body can be
used to determine body composition.
• Based on the principle that the resistance to an
applied electric current is inversely related to the
amount of fat-free mass within the body.
• Measurement affected by hydration status, time of day
and body temperature
Dual-Energy X-Ray Absorptiometry
(DEXA)
• The DEXA instruments
differentiate body weight
into the components of lean
soft tissue, fat soft tissue
and bone, based on the
differential attenuation by
tissues of two levels of xrays.
• Requires trained radiology
personnel to operate.
• The most accurate body fat
analysis
Bod Pod
• The amount of air displaced by a person in
a small chamber is measured by
computerized sensors.
Setting Body Composition Goals
• If fat loss would benefit your health, set a
realistic goal in terms of percent body fat
or BMI
• If you have underlying health issues,
check with your physician before setting a
goal
• A little weight loss at a time can be very
beneficial; focus on a healthy lifestyle
including proper diet and exercise
Making Changes in Body Composition
• Lifestyle should focus on:
–Regular physical activity,
endurance exercise, and
strength training
–Moderate energy intake
• Physical activity is the key to longterm success