Metabolism cont’d, Body Composition

Body Composition The slides in this power point are a valuable reference to be used with your body composition lab calculations.

Two-Component Model Partitions the body into two distinct compartments –Fat-free body mass (FFM) –Fat mass (FM) Tissue densities –Fat-free body tissue: g/cm 3 –Adipose tissue: g/cm 3

Essential Fat Essential fat –~3% of body mass –Consists of fat stored in the marrow of bones, heart, lungs, liver, spleen, kidneys, intestines, muscles, and lipid-rich tissues of the central nervous system Sex-specific fat (Females) –~9% of body mass –Essential for childbearing and other hormone- related functions

Storage Fat Consists of fat accumulated in adipose tissue depots Storage fat includes –Visceral adipose tissue –Subcutaneous adipose tissue

Lean Body Mass (LBM) vs. Fat-Free Body Mass (FFM) LBM is a theoretical entity LBM contains the small percentage of non–sex-specific essential fat FFM represents the body mass devoid of all extractable fat FFM = Body Mass – Fat Mass

Minimal Leanness Standards Men –Fat-free mass –3% essential fat Women –Fat-free mass –3% essential fat –9% sex-specific fat

Criteria for Underweight Female Body mass lower than minimal body mass calculated from skeletal muscle measurements Body mass lower than the 20th percentile by stature Percent body fat lower than 17% as assessed by a criterion method

Menstrual Cycle Disturbances Delayed-onset menstruation Oligomenorrhea –Irregular menstrual cycles Amenorrhea –Complete cessation of menses –In the general population, occurs in 2 to 5% of women of reproductive age –May occur in as many as 40% of women participating in sports

Methods to Assess Body Size and Composition FM and FFM are assessed by: –Direct measurement by chemical analysis or dissection –Indirect estimation by hydrostatic weighing, anthropometric measurements, and other simple procedures including body stature and mass

Methods to Assess Body Size and Composition