Development of equations based on Body Mass Index to estimate fat mass in older people

Abstract

Background: Excess fat mass (FM) has a higher risk of producing sarcopenia, physical deterioration and reduced quality of life in older people. Aim: To propose regression equations based on the Body Mass Index (BMI) to predict fat mass using double energy X-ray absorptiometry (DXA) as the gold standard. Material and Methods: Cross-sectional study in 1,188 participants (523 men and 665 women) aged 60 to 85 years. Ten percent of these (59 men and 60 women) were randomly selected to propose FM equations using DXA. The remaining 90% was used to calculate FM and develop percentiles. Results: Two equations were proposed to estimate FM [men: FM = -29,502+ (1,912 * BMI) R2 = 79%, women: FM = -9,891+ (1,323 * BMI) R2 = 80%]. Ten, 50, 85 and 95 percentiles were developed to evaluate FM. Conclusions: This study developed reliable regression equations and referential values to estimate FM in older people.