Relationship between Bioelectrical Impedance Analysis and Body Mass Index in Adolescent Urban Nigerians

BACKGROUND: Body mass index is often used to assess adiposity but it does not differentiate between fat and non-fat components of body mass. However, body fat composition may be assessed using bioelectrical impedance analysis. OBJECTIVE: The study aimed to relate body mass index to fat in the assessment of overweight and obesity among adolescent Nigerians. METHODS: Adolescent pupils aged 10years to 18years from randomly selected secondary schools in Lagos, Nigeria were studied. Body mass index was calculated while percentage body fat was measured using Tanita body® fat scale model BF 681. Overweight and obesity were defined using age and sex specific criteria for body mass index and for body fat. RESULTS: There were 753 pupils {377(50.1%) males and 376(49.9%) females}. The overall mean body mass index for males and females were 18.1±2.72 and 18.9±3.41 (p < 0.05) respectively. The corresponding figures for body fat were 9.5±4.48 and 18.9±7.51 (p<0.05) respectively. About three quarters (76.2%) of the females who had body mass index in the overweight/obesity range had high body fat in comparison to 44.4% of males (p < 0.05). CONCLUSION: Body mass index is more related to body fat in adolescent females than in their male counterparts.