Introduction: Postmenopausal women have excess adiposity due to the lack of estrogens, which is related with an increase in the prevalence of metabolic syndrome (MS) risk factors. Few equations have been developed to measure body fat mass (FM) by bioelectric impedance (BIA) for Mexican women and none of the existing equations have been evaluated in Mexican postmenopausal women with MS.
Material and methods: We describe the association and agreement between two different BIA equations: NHANES III and Macias, et al. to estimate FM in 86 women (42-72 years old). Anthropometric and body composition measurements (BIA) were done in all women; FM was measured by densitometry (DXA). Mean differences by age group (< 55 years old and > or = 55 years old) (Student t test), correlations, simple linear regression models and agreement analysis (Bland-Altman method) were done.
Results: The two equations showed underestimation of % FM compared to DXA. The equation that presents the greatest correlation and agreement with the gold standard is the NHANES equation, in both age groups.
Conclusions: The NHANES equation is valid to estimate FM in Mexican postmenopausal women with MS. We recommend the use of this equation in the clinical practice.