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Body Composition
most methods consider body having two components:– fat component, i.e. fat mass– fat-free component, i.e. fat-free mass (FFM)
body fat % is the % of total body weight– average values: women, ~25%; men ~15%– minimal values: women, 8-12%; men – 5%– considered obese: women, >30%; men >20%
essential and non-essential fat
Reference body composition components for men and women
Ratings of % Fat (ages 20-29 yr)
Rating Men Women
Excellent 6-9 10-17 Good 10-14 17-21 Acceptable 15-19 21-25 Too Fat 20-22 27-32 Obese >22 >32
Determining Ideal Body Weight
Indirect approaches Metropolitan height–weight tables body mass index (BMI)
– weight (kg) / height2 (m2)– ideal range is 18-25– >30 considered obese
Direct approaches hydrostatic (underwater) weighing anthropometric (skin-fold) measurements bioelectrical impedance analysis (BIA)
Dr. Kolkhorst Dr. Buono
Kolkhorst Buono
Hydrostatic (Underwater) Weighing
determines body density principles involved:
– fat is less dense than water– FFM is more dense than water
assumptions:– fat density is 0.9007 g/cm3
– FFM density is 1.1000 g/cm3
SE = 2.5 - 3.0 % accuracy influenced by sex, age, race,
muscle mass, RV determination
Anthropometric (Skinfold) Measurements
>100 equations available from which to choose
most commonly used–and most accurate–are generalized equations by Jackson et al.
SE = 3.5 - 4.0% accuracy affected by extremes in age, % fat,
race
Bioelectrical Impedance
dual-energy X-Ray absorpitometry (DXA)– Perhaps most accurate
method
air-displacement plethysmography (BOD POD)– measures change in BOD
POD volume and subject’s weight
Suggested Reading on Body Composition
Houtkooper, L.B. and S. Going. Body Composition: How should it be measured? Does it affect sport performance? 7(5), SSE#52, 1994. http://www.gssiweb.com
Body Composition and Sport Performance
clear relationship between low % fat and better performance
Question: What is ideal % fat? potential consequences of large weight loss:
– chronic fatigue– Female Athlete Triad
ACSM Position Stand papers
Nutrition and athletic performance – http://www.acsm-msse.org/pt/pt-core/template-jour
nal/msse/media/1200.pdf
Weight loss strategies – http://www.acsm-msse.org/pt/pt-core/template-jour
nal/msse/media/1201.pdf
You measure a 21-year old man to have 18.2% body fat.
A. He should lose some body fat.
B. He is at an ideal weight.
C. He is underweight.
A subject who weighed 200 lb was estimated from an underwater weighing test to be 20% fat.
What is his fat-free mass?
A. 20 lb
B. 120 lb
C. 160 lb
D. 180 lb
E. 200 lb
F. cannot be determined
Weight Management
Weight change = energy intake – energy expenditure
Energy Intake caloric density
– CHO = 4 kcal/g– protein = 4 kcal/g– fat = 9 kcal/g– ethanol = 7 kcal/g
influence of diet composition
Your girl/boy-friend gives you part of her/his Snicker’s candy bar. It contains 6 g of fat and there is 100 kcal of energy. What is the percentage of energy that comes from fat?
a. 6 kcal
b. 600 kcal
c. 6%
d. 54%
e. 60%
f. cannot be determined
Snicker’s bar contains 6 g of fat and has 100 kcal of energy– fat has 9 kcal of energy per g – 6 g 9 kcal/g = 54 kcal from fat– 54 kcal (fat) / 100 kcal (total) = 54%
Weight ManagementCalculate % Intake from Fat
Breakfast - McDonald's Energy(kcal)
Fat(g)
Sausage McMuffin w/Egg 517 331% Milk - 8 oz 110 2Hash Brown Potatoes 125 7
Lunch - Burger King Bacon Double Cheeseburger 510 31French Fries - regular 227 13Chocolate Shake - 10 oz 374 11
Snack Snicker's Candy Bar 280 13
Dinner - Taco Bell Two Tacos 372 16Combination Burrito 404 16Pepsi - 24 oz 288 0
TOTAL (40% of intake from fat) 3,207 142
Weight Management
Energy Expenditure basal metabolic rate (BMR) affected by:
– energy intake– exercise
activity / exercise
Weight ManagementEnergy Expenditure (kcal/min)
Activity 123 lb 183 lb basketball 7.3 11.5Circuit training 9.8 15.4Cycling (9.4 mph) 5.6 8.3Running (9 min/mile) 10.8 16.0Running (7 min/mile) 13.3 18.5Swimming (slow) 7.2 10.6Swimming (fast) 8.7 12.9Tennis (singles) 6.1 9.0Walking (3.0 mph) 4.5 6.6Sitting (quietly) 1.2 1.7
Effects of low-energy intake on
RMR
Bray, Lancet, 1969
Effects of low-energy intake and exercise on RMR
Effect of energy intake on RMR
Female Athlete Triad
female athletes most prone to
eating disorders, affects 30-65%
R = regular mensesO = oligomenorrheaA = amenorrhea
Relationship between vertebral bone mineral density (BMD) and menstrual history
Suggested Reading on Female Athlete Triad
The Female-Athlete Triad. 8(1), RT# 27, 1997. [Roundtable Discussion] http://www.gssiweb.com
A very low-energy diet would likely ____ the resting metabolic rate.
a. increase
b. decrease
c. have no effect on
Young female athletes who are not menstruating or have irregular menstruation,
a. may not be consuming enough energy.
b. are at increased risk of osteoporosis.
c. both of the above are correct