Table 1.

Comparative advantages and disadvantages of a selection of in-vivo body composition assessment methods.

	Method	Advantages	Disadvantages
Direct	Whole body counting	High accuracy	Costs, technical difficulties.
Indirect	Densitometry (underwater weighing, air-displacement plethysmography)	Relatively fast and non-invasive	Costs, hydration assumptions, effects of disease on lean mass reduce accuracy, distribution of fat unable to be determined.
	Hydrometry (D2O, NaBr)	Suitable for all age group	Costs, low acceptability, delayed results.
	Dual-energy X-ray Absorptiometry (DXA)	Reliable and repeatable. Can provide regional as well as total evaluations	Small radiation exposure. Can overestimate fat mass.
	Magnetic resonance, computed tomography	High reproducibility, accurate assessment of lean soft tissue, assessment of regional adiposity and of intra-abdominal vs subcutaneous adiposity.	Costs, not suitable for all infants due to need for transfer to scanner and time required for scan acquisition. Computed tomography involves the use of X-rays, which are a form of ionizing radiation.
Double Indirect	Anthropometry	Simple measurement of subcutaneous fat	Population specific, poor accuracy in individuals and groups, training required.
	Bioelectric Impedance Analysis (BIA)	Quick and non-invasive. Cumulative accuracy makes useful for repeated measures	Population specific. Distribution of fat unable to be determined.