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 yr)

Determining Ideal Body Weight Indirect approaches Metropolitan height–weight tables body mass index (BMI) –weight (kg) / height 2 (m 2 ) –ideal range is –>30 considered obese Direct approaches hydrostatic (underwater) weighing anthropometric (skin-fold) measurements bioelectrical impedance analysis (BIA)

Dr. KolkhorstDr. 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 g/cm 3 –FFM density is g/cm 3 SE = % 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 = % 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,

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 – journal/msse/media/1200.pdfhttp:// journal/msse/media/1200.pdf Weight loss strategies – journal/msse/media/1201.pdfhttp:// journal/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 Management Calculate % Intake from Fat

Weight Management Energy Expenditure basal metabolic rate (BMR) affected by: –energy intake –exercise activity / exercise

Weight Management Energy Expenditure (kcal/min)

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

Weight Management diet modification physical activity modification behavior modification Principles Common to Successful Programs

Weight Management Behavior Modification avoid automatic eating plan meals ahead of time don’t serve self more food than should eat avoid social binges practice other stress management techniques set realistic goals incorporate physical activity into program

Weight Management Summary lose weight slowly (i.e.  2 lb/week)  energy intake  fat intake  complex CHO and fiber intake exercise regularly (3-5 X/week) modify eating habits/attitudes

Female Athlete Triad female athletes most prone to eating disorders, affects 30-65%

R = regular menses O = oligomenorrhea A = 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, [Roundtable Discussion]

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