Body Composition
Body frame-size (BFS) Female: *Ht. + (biacromial + bitrochanteric) Male: 8.239*Ht. + (biacromial + bitrochanteric)
Body frame-size (BFS)
BFS Limitations zUnvalidated estimates of body frame size zDeveloped primarily from white population zFocus on mortality data - not obesity related comorbidities zNo assessment of body composition
BMI Body mass (kg) height (m 2 ) optimal range: or from optimal range of disease* * CAD, HTN, CVA, DM, CA, etc.
BMI Determine the BMI for: zMale zweight = 100 kg zheight = 2 m
BMI Limitations zfails to consider composition of body zfat
BMI zGenerally related to body composition zHighly correlated w/ relative body fat zprobably provides a better estimate of obesity
BMI Overweight (1998) zmales 27.8 25 zfemales 27.3 25 zobese: > 30
BMI
Population Overweight
z25% of all US adults z33.4% z47.2% Mexican-American women z48.6% African-American women
Leanness in Women Active low weight women are at risk of: zdelayed onset of menstruation zirregular menstrual cycle (oligomenorrhea) zcessation of menses (amenorrhea)
Leanness in Women Hypotheses: zExercise Stress (disruption of hypothalamic- pituitary-adrenal) zEnergy Availability yenergy reserve inadequate to sustain pregnancy y< 17% cessation / 22% normal cycle
Body Composition Models
Body Composition Total Body-Fat (Fat-Mass) = Essential Fat + Storage Fat Essential Fat (survival) zCNS zBone Marrow zOrgans (heart, liver, kidneys, spleen, etc.)
Fat-Free Mass vs. LBM LBM includes essential fat zLBM = Body Mass - Storage Fat FFM excludes essential fat zFFM = Body Mass - Total Body Fat
Behnke Model: Males
Behnke Model: Females
Body Composition 100 kg male w/ 20% body fat zBody mass: 100 kg zStorage Body Fat: 100 *.20 = 20 kg zLean Body Mass = = 80 kg - includes 5% essential fat
Body Composition zFat Free Mass = Body Mass - Total Fat Mass zTotal Fat Mass = 20 kg + 4 kg (essential fats) zFat Free Mass = = 76 kg
Importance of Body Fat DietExerciseCombination
Importance of Body Fat
Measuring Body Fat Direct zchemical analysis zdissection Indirect
Measuring Body Fat Hydrostatic Weighing / Densitometry zbody volume = loss of weight in H 2 0 (scale wt. - underH 2 O wt) z“gold standard” zbased on assumptions
Measuring Body Fat Skinfolds/Fatfolds Girth Measurements Bioelectrical Impedance Analysis (BIA) zconduction is better thru non-fat z H 2 0 impedance % body fat
Measuring Body Fat Near-Infrared Interactance (NIR) zFutrex-5000 zfiber optic zbiceps of dominant arm zvalidity????
Measuring Body Fat US Arm X-Ray (3 site) CT scan MRI DEXA (Dual-energy X-Ray Absorptiometry) - bony mineral content - r =
Desirable Body Mass Males zstrive for 15% z< 20% Females zstrive for 25% z< 30%
Desirable Body Mass z200 lbs. individual zWants to reduce % body fat from 20% 10% zWhat is this individual’s desirable weight?
Desirable Body Mass Desirable Body Mass (DSB) = fat-free body mass / ( desired % fat) Current fat-free body mass = (200 * 0.20) 160 lbs.
Desirable Body Mass Desirable Body Mass (DSB) = fat-free body mass / ( desired % fat) DSB = (160 / ( ) 160 lbs. / lbs.
Desirable Body Mass What is the loss in body weight? z 200 lbs lbs. = 22 lbs.
General Guidelines for Weight Loss- Athlete z preserve FFM z kcal < daily energy expenditure z resistance and endurance training