Body Composition zFat -free mass zBody Fat yessential ynon-essential

Further divide body into components zfat zwater zbone zmuscle zorgan tissue zother (nerves, connective tissue, etc)

Ideal Body Composition zhealth zaesthetics zperformance

Healthy fat percentage z16-25% for females z< 20% for males

Aesthetic body composition zlean look is prized and admired zdesire can lead to eating disorders

Performance body composition zsport-specific zsome sports have specific weight classes ywrestling, boxing, weight lifting zvariability depends on the metabolic requirement of the activity and on the disadvantage of carrying extra weight zproblems when individuals try to gain too much weight or lose too much

Measuring Body Composition zTwo component models yhydrostatic weighing (underwater) yskinfolds zMultiple component models yBIA yDXA yTOBEC yBiochemical

Assumptions of measuring composition zdissection is most accurate zmost indirect methods are based on cadaver studies zcadaver studies: small n (8), one female zfat mass gm/ml zfat-free mass gm/ml

Cadaver studies zoriginal work in 1940s zdid not compare to other methods, just direct measurement zassumed density of gm/ml extrapolated to humans from guinea pigs zuntil can validate a method directly, it is an estimate zall of the methods have limitations

Hydrostatic Weighing zUntil DXA, most accurate method zbased on Archimedes’ Principle of water displacement and density zprocedural difficulties

Dual Energy X-Ray Absorptiometry zdeveloped to determine bone content and subsequently, density zmay replace hydrostatic weighing as the gold standard zrelies on fewer assumptions about human tissue zcan use animals to directly validate the technique

Biochemical Techniques zpotassium analysis ztotal body water zintert gas absorption

Anthropometric and Skinfolds zBMI zWaist Circumference and Waist-Hip Ratio zSomatotype zAnthropometric zSkinfolds

Ultrasound, Computerized Tomography (CT), and Electrical Impedance zultrasound: technology used by cardiologists, estimate thickness of tissues zCT: x-ray that provides a three- dimensional view of the body

zTotal Body Electrical Conductivity (TOBEC): surrounds body with magnetic field and measures the rate at which the body conducts electrical energy zBioelectrical Impedance Analysis (BIA): measure impedance to flow in opposite extremities