The characteristics of available methods for measuring body composition
| Method | Primary measurements | Advantages | Disadvantages |
|---|---|---|---|
| BIA/BIS | TBW, extracellular and intracellular fluid spaces | Inexpensive, portable, simple, safe, fast | Population specific, poor accuracy in individuals and groups |
| DEXA | Total body fat, lean mass, regional body fat, bone mineral content and BMD | Easy to use, low radiation exposure, accurate for lean and fat mass of limb | Biased by body size, sex, fatness; specialized technician required to operate |
| QCT | Specific regional bone density | High accuracy and reproducibility | High radiation exposure, expensive |
| Dilution techniques | TBW and extracellular fluid | Acceptable in all age groups, easy to administer isotopes | Inaccurate if used in disease states, expensive, labor for analyses |
| Air displacement plethysmography | Total body volume and total body fat | Relatively high accuracy, fast | Reduced accuracy if used in disease states, expensive |
| Three-dimensional photonic scanning | Total and regional body volume | Acceptable in extremely obese persons, easy to use, suitable for both research and clinical applications | Few scanners available thus far |
| QMR | TBW and total body fat | Easy to use, safe, fast | Expensive, few systems available thus far |
| MRI/MRS | Total and regional adipose tissue, skeletal muscle, organs, lipid content in liver and muscle | High accuracy and reproducibility for whole body, regional adipose tissue and skeletal muscle | Expensive |
BIA, bioelectrical impedance analysis; BIS, bioimpedance spectroscopy; BMD, bone mineral density; DEXA, dual energy X-ray absorptiometry; MRS, magnetic resonance spectroscopy; QCT, quantitative computed tomography; QMR, quantitative magnetic resonance; TBW, total body water.