An anthropometry-based equation of fat mass percentage as a valid discriminator of obesity

Objective: To develop a new predictive equation for fat mass percentage (%FM) based on anthropometric measurements and to assess its ability to discriminate between obese and non-obese individuals. Design: Cross-sectional study. Setting: Mexican adults. Participants: Adults (n 275; 181 women) aged 20-63 years with BMI between 17.4 and 42.4 kg/m ² . Results: Thirty-seven per cent of our sample was obese using %FM measured by air-displacement plethysmography (BOD POD®; Life Measurement Instruments). The fat mass was computed from the difference between weight and fat-free mass (FFM). FFM was estimated using an equation obtained previously in the study from weight, height and sex of the individuals. The %FM estimated from the obtained FFM showed a sensitivity of 90.3 (95 % CI 86.8, 93.8) % and a specificity of 58.0 (95 % CI 52.1, 63.8) % in the diagnosis of obesity. Ninety-three per cent of participants with obesity and 65 % of participants without obesity were correctly classified. Conclusions: The anthropometry-based equation obtained in the present study could be used as a screening tool in clinical and epidemiological studies not only to estimate the %FM, but also to discriminate the obese condition in populations with similar characteristics to the participant sample.