Table 1

 Summary of assumptions underlying different techniques, their availability, and their main advantages and disadvantages

TechniqueAssumptions madeReference dataAvailability*Advantages/disadvantages
*Availability: +, low; ++, medium; +++, high.
†Densitometry by air displacement plethysmography (Bodpod)
AT, adipose tissue; Df, density of fat; Dffm, density of fat-free mass; Dmin, density of mineral; Dprot, density of protein; F, fat; FFM, fat-free mass; Hffm, hydration of fat-free mass; K, potassium; Var, variability.
Skinfolds – rawConstant skin protein contentY+++For: simple measure of regional fat
Against: no information on lean mass
Skinfolds – equationsSkinfolds ∝ whole body fatN+++For: simple and quick
Against: population specific, poor accuracy in individuals and groups
Body mass indexVar weight  =  var fatY+++For: simple and quick
Against: measures nutritional status not body composition
Waist circumferenceWaist ∝ central fatY+++For: simple, quick, robust measure of abdominal fat
Against: not so accurate as measure of internal visceral fat
ImpedanceConductivity ∝ body waterN++For: simple and quick
Against: population specific; poor accuracy in individuals and groups
DXAConstant attenuations of FFM and FN++For: accurate for limb lean and fat
Against: radiation exposure; whole body bias ∝?size, sex, fatness
Densitometry†Constant Dffm and DfN+For: acceptable two-component technique
Against: effects of disease on lean mass reduce accuracy
Isotope dilutionConstant HffmN+For: only technique acceptable in all age groups
Against: delayed results; inaccurate if disease affects Hffm
MRIElectromagnetic propertiesN+For: accurate for regional AT
Against: expensive, limited availability, measures AT not fat
TOBECConductivity ∝ body waterN+For: acceptable two-component technique
Against: rarely available, accuracy unknown
TBKConstant K in cell massN+For: measures functional component of body composition
Against: rarely available, poor accuracy for fatness
Multicomponent modelsConstant Dprot and Dmin,N+For: most accurate approach, all measurements acceptable
constant mineral compositionAgainst: expensive, specialist research approach