Validity of skinfold thickness measures of formerly obese adults.

ABSTRACT

UNLABELLED To assess the validity of skinfold thickness estimates of body fatness in formerly morbid obese adults, 23 patients (17 women, 6 men) who had completed a protein-sparing modified fast were studied. Mean +/- SD weight loss was 60.7 +/- 20.6 kg for men and 42.6 +/- 11.5 kg for women. Body density and percent body fatness were determined after weight loss according to four commonly used skinfold equations Pollock (P); Durnin-Rahaman (D-R); Durnin-Womersley (D-W); and, Jackson-Pollock (J-P). The validity of these measurements was assessed by hydrostatic weighing, which revealed a percent body fatness of 20.4 +/- 6.5 for men and 29.8 +/- 8.4 for women. The mean difference and total error (square root of the mean of squared deviations) between skinfold predicted and hydrostatically-determined percent body fatness for each skinfold equation were P, 2.0 and 4.9; D-R, 4.2 and 6.6; D-W, 7.1 and 8.4; and, J-P, 0.7 and 4.4. With the exception of the latter equation, all significantly overestimated (p less than 0.01) hydrostatically-determined percent body fatness. CONCLUSION: Select skinfold equations may result in a marked overestimation of body fatness in formerly obese patients.