Body fat: Estimation or guesstimation?

Skinfold anthropometry is performed world-wide with little appreciation of its limitations. This paper shows that it is important to appreciate the magnitude of the biological component of the residual error in any regression of body density against sums of skinfolds; for example, for young adult males a biological error of around 21% (s.d.) is observed. Such ‘errors’ simply express natureʹs refusal to conform to imposed regression relationships, reflecting the inherent variability in the ratio of subcutaneous to total body fat.