Body composition assessment (revision 2)
Old revision·15:14, 13 Nov 2024·HOMA_Hettie
| Body composition assessment | |
|---|---|
| Reference methods | DXA, four-compartment models |
| Field methods | Bioimpedance, skinfolds, circumference |
| Limitation of weight alone | Cannot distinguish the compartments |
| Analytical method infobox · conventions | |
Body composition assessment measures the fat and lean compartments of the body separately. Body weight cannot distinguish them, and a given weight change may comprise very different proportions of each.[1]
The reference methods are dual-energy X-ray absorptiometry and multi-compartment models combining several measurements. Field methods — bioimpedance, skinfolds, circumference-based equations — are more accessible and considerably less precise.[1]
Methods and their precision
[edit]| Method | Basis | Precision for change |
|---|---|---|
| DXA | Differential X-ray attenuation | Good; the practical reference |
| Four-compartment model | Combines density, water, mineral | Best available; research only |
| Bioimpedance | Electrical conductance | Sensitive to hydration state |
| Skinfolds | Subcutaneous thickness | Operator-dependent |
| Circumference equations | Anthropometric proxies | Population-derived; poor for individuals |
Bioimpedance is the method most often used outside research and the one whose limitations are least appreciated. It infers composition from conductance, which depends on total body water; changes in hydration produce apparent changes in lean mass that did not occur.[1]