Prevalence of Overnutrition using Body Mass Index in Comparison with Bioelectrical Impedance Analysis among Children and Adolescents in Benin, Nigeria

Aim: To compare the prevalence of overweight and obesity among school children in Egor Local Government Area (LGA) using body mass index (BMI) and bioelectricial impedance analysis (BIA) and determine the ability of body mass index (BMI) to predict body fat mass as measured by bioelectricial impedance analysis (BIA).

Study Design: This was a cross sectional study conducted in Egor Local Government Area of Edo State of Nigeria with1067 children aged 6-18 years recruited from private and public schools. Body mass index was calculated as weight in kilograms divided by the square of height in meters while Body fat was estimated by BIA using a Tanita scale.

Place and Duration of Study: The study took place in selected private and public primary/secondary schools in Egor LGA of Edo State. The study was conducted over a three-month period from October to December 2017.

Methodology: Using multi-stage sampling technique,1067 children aged 6-18 years were recruited from private and public schools in Egor Local Government Area in Benin City, Nigeria. Body fat was estimated by BIA using a Tanita scale, whereas BMI was calculated as weight in kilograms divided by the square of height in meters. Data was analyzed using SPSS version 21.

Results: A total of 1067 pupils consisting of 538 (50.4%) males and 529 (49.6%) females were recruited. The overall prevalence of overnutrition by BMI, 13.4% (overweight 9.6% and obesity 3.8%) was comparable to that by BIA which was 12.4% (overweight 5.4% and obesity 6.9%). BMI showed a strong positive correlation with fat mass, and fat mass index especially in females (0.917, 0.907, p < 0.000).

Conclusion: The prevalence of overnutrition using BMI and BIA was comparable. The prevalence of obesity is however underestimated with BMI.