Endocrine Abstracts

Introduction: A simple linear anthropometric linear equation for total body fat quantification in adults was recently selected as the best of 365 anthropometric indexes in the American population. The authors intend to evaluate the correlation between the relative fat mass (RFM) equation and body fat determination by electric bioimpedance (EB) and compare it with BMI.

Material/methods: Retrospective, cross-sectional, observational study that selected all ambulatory patients with body composition determined by EB in our obesity department. Clinical data and prescriptions were collected from the electronic records. A total of 897 cases were evaluated from 2006 to 2018. The calculated RFM [64−(20×height/waist)+(12×sex)] was compared with BMI. We used descriptive statistics presented as mean and standard deviation, student’s t-test and Pearson Correlation for the nominal variables. For the categorical χ² was used. The level of significance accepted was P<0.05.

Results: Of the 897 patients, 82.6% were female, with a mean age of 46.2±11.3 years at the first visit. The majority (84%) was submitted to bariatric surgery; the prevalence of type 2 diabetes, hypertension and dyslipidemia were high in this population. The mean fat mass was 32.1±10.2%, RFM 43.2±6.1 and BMI 35.7±7.3 kg/m². The correlation between RFM and percentage of fat mass was stronger than the correlation between the latter with BMI (P<0.001) r=0.70 vs 0.66, respectively.

Conclusions: Our analysis suggests that RFM, compared with BMI, had a stronger correlation with body fat mass determined by EB. Although being EB described as a less accurate body fat evaluation technique, our results are consistent with the available literature, which often uses dual-energy X-ray absorptiometry (DXA) as the gold standard.

Keywords: obesity, RFM, BMI, Body fat mass, bioimpedance