Compare and contrast various body fat assessment techniques

Question

What will be an ideal response?

Answer 1

Dual energy X-ray absorptiometry (DXA): considered the standard technique to assess body composition, with ±1.8 percent SEE; uses very low-dose beams of X-ray energy (hundreds of times lower than a typical body X-ray) to measure total body fat mass, fat distribution pattern, and bone density; not readily available to most fitness participants.
Hydrostatic weighing: the most accepted standard in fitness laboratories, against which the other techniques are validated; a person's "regular" weight is compared with a weight taken underwater because fat is more buoyant than lean tissue; the SEE is 2.5 percent; requires considerable time, skill, space, and equipment; must be administered by a well-trained technician; not feasible for large groups; not feasible for aquaphobic individuals (those not comfortable in water); requires a residual volume (RV) measurement in the lungs to be accurate. If RV cannot be measured, the accuracy of hydrostatic weighing is decreased.
Air displacement: uses the Bod Pod to estimate volume of the body; computerized pressure sensors determine the amount of air displaced by the person inside the chamber; compares favorably with hydrostatic weighing and is easy to administer; the current SEE for air displacement as compared to hydrostatic weighing is approximately ±2.2 percent; is expensive and not yet tested with population-specific groups.
Skinfold thickness: based on the principle that the amount of subcutaneous fat is proportional to total body fat; seems to be the most practical and valid technique to estimate body fat (other than hydrostatic weighing or air displacement); the SEE for skinfold analysis is ±3.5 percent; administered using pressure calipers that measure (in millimeters) a number of folds on the right side of the body; measurements should be done at the same time of the day and by the same technician for pre- and post-test measurements.
Girth measurements: administered using a measuring tape to assess the circumference of various body parts. Assumes an average amount of muscularity, so it is not valid for very active, thin, and obese individuals. The SEE for girth measurements is approximately 4 percent. Three girth measurements are taken for women and two for men.
Bioelectrical impedance: based on the principle that fat tissue is a less efficient conductor of electrical current than lean tissue. Comes in hand-held instrument or standing "bathroom" scale forms. Is simple to administer, but its accuracy is questionable. May be off by as much as 10 percentage points or more.