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Assessment of fat-mass loss during weight reduction in obese women

1997; Elsevier BV; Volume: 46; Issue: 8 Linguagem: Inglês

10.1016/s0026-0495(97)90089-5

1532-8600

Mikael Fogelholm, Harri Sievänen, Wouter D. van Marken Lichtenbelt, Klaas R. Westerterp,

Thermoregulation and physiological responses

Methods for assessing body fat mass (FM) loss were compared in 32 obese (body mass index [BMI], 29 to 41 kg/m2) premenopausal women before and after a weight loss of 13.0 ± 3.4 kg (mean ± SD). A four-component (4C) model was used as the criterion. The other methods were as follows: three-component models (body density with total body water [3W] or bone minerals [3M]), underwater weighing, dual-energy x-ray absorptiometry ([DXA] XR-26, software 2.5.2; Norland, Ft Atkinson, WI), bioelectric impedance analysis (BIA) with an obese-specific equation (Segal et al), skinfolds (Durnin and Womersley), and an equation with BMI (Deurenberg et al). The 3W model (bias ± SD, 0.5 ± 0.4 kg), XR-26 (0.6 ± 2.1 kg), and BMI equation (−0.3 ± 2.1 kg) gave practically unbiased mean estimations of fat loss. All other methods underestimated fat loss by at least 1.6 kg (range of bias, −2.7 to −1.6 kg). The small bias (0.7 ± 1.0 kg) between underwater weighing and model 4C before weight reduction indicates that the two-component assumptions were valid in premenopausal, weight-stable obese women. However, particularly the water fraction of the fat-free body component (4C model) was increased after weight reduction (before, 72.9% ± 1.4%; after, 75.7% ± 2.2%), making both underwater weighing and the 3M model uncertain for assessment of body composition changes. A general tendency for overestimating FM was seen before and more clearly after weight reduction. However, most methods underestimated fat loss, apparently because of unexpected changes in hydration of the fat-free body component.