Transcript Slide 1

Chapter 6 Lecture
Body
Composition
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Learning Objectives
• Define body composition
• Explain the relationship between body fat
percentage and disease risk
• Explain the concept of optimal body weight
• Discuss the importance of assessing body
composition
• Explain body composition assessment using
hydrostatic weighing, the skinfold test, body
mass index, and waist-to-hip circumference ratio
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Body Composition
• The relative amounts of fat and fat-free tissues
(bone, muscle, organs) in the body
• Expressed as percentage of fat in the body
– Overweight
– body fat percentage above the recommended level
– Obesity
– >25% body fat for men
– >35% body fat for women
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Body Composition Relationship to Health
Essential Fat
• Located in nerves and cell membranes
• Necessary for body functioning
• 3% for men
• 12% for women
Storage Fat
• Located in adipose tissue
• visceral (around organs)
• subcutaneous (below the skin)
• 8–19% for men, recommended low end of 12–15%
for young adult
• 21–32% for women, recommended low end of 21–
25% for young adult
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Storage Fat
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Body Composition Relationship to Health
Android Pattern of Obesity
• Fat is primarily stored in upper body and
around the waist
• Most common in men
• Greater risk of developing heart disease and
diabetes
Gynoid Pattern of Obesity
• Fat is primarily stored in waist, hips, and
thighs
• Most common in women
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Health Risks Associated with Levels of
Body Fat
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Overweight and Obesity in the United States
• Current obesity estimates
– 34% of adults
– 17% of children/adolescents ( 2–19 yrs.)
• NIH estimates obesity directly contributes to 15–20% of deaths in
United States
• Contributes significant effect on health care costs
– 10% of all medical costs in United States
– $147 billion per year direct medical costs
– predicted to rise sharply in future
• WHO indicates U.S. obesity rates highest in world
– in 2010 every state had 20% or higher obesity rate
– 36 states 25% or more
– 12 states 30% or more
• Adult rates are leveling off
• Childhood obesity rates show NO evidence of decreasing
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Obesity Rates in United States
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Creeping Obesity
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Chronic Conditions of Overweight and
Obesity
• Heart disease (also called cardiovascular
disease or CVD)
• Diabetes
• Cancers (breast, prostate, colon)
• Joint problems and osteoarthritis
• Sleep apnea
• Gallbladder disease
• Menstrual abnormalities
• Difficulty with conception and pregnancy
complications
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Benefits of a Healthy Weight
Mental Benefits
• Better self-esteem & body image
• More positive mindset
• Less anxiety and depression
Physical Benefits
• Lower risk of diabetes, cardiovascular
disease, and cancer
• Easier motion for physical activity and
everyday living
• Lower death rate
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Health Effects of Underweight
• Loss of muscle mass and strength resulting from
malnutrition
• Osteoporosis
• Menstrual abnormalities that can lead to infertility
Severe underweight from eating disorders (anorexia
nervosa and bulimia) can lead to
• Heart problems
• Digestive disorders
• Kidney damage
• Anemia
• Lethargy
• Muscle weakness
• Dry skin
• Compromised immune function
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Assessing Body Composition
Field Methods
• Height/weight tables
• Body mass index (BMI)
• Skinfold test
• Waist measurement & waist-to-hip ratio
Laboratory Measures
• Dual energy X-ray absorptiometry (DXA)
• Hydrostatic weighing
• Air displacement
• Bioelectrical impedance analysis (BIA)
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Estimating BMI
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Relationship Between BMI and % BF
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Determining Ideal Body Weight
• Calculate % body fat and select a healthy body fat %
range based on sex and age
– Example: Male – age 25, weight 185 lb, 30% body fat,
body fat % range of 8–19% recommended
• Step 1. Compute fat-free weight
– Total body weight – fat weight = fat-free weight
– 100% – 30% body fat = 70% fat-free weight
– 70% x 185 lb = 129.5 lb fat-free weight
• Step 2. Calculate optimal weight
– Optimal weight = fat-free weight/(1 – optimal % fat)
– 129.5/(1 – .08) = 140.8 lb optimal weight
– 129.5/(1 – .19) = 159.9 lb optimal weight
• See Lab 6.2 worksheet to determine ideal body weight
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Weight Management
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Set goals
Get regular body fat assessments
Re-evaluate optimum weight over time
Guard against lean mass loss during weight loss
Incorporate regular aerobic and resistance
exercise
• Eat a healthy diet
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Summary
• Body composition is the relative amounts of fat and fat
free tissue in the body
• A high percentage of body fat is associated with
increased risk for numerous diseases
• Body fat distribution also affects disease risks associated
with overweight and obesity
• Common field techniques for estimating body fat include
skinfold measurements, BMI assessment, and waist-tohip ratio
• DXA is considered the gold standard measure for
estimating body fat
• Get regular body composition assessments while trying
to lose or gain weight
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