Assessment of Body Fat Using Leg-to-leg Bioelectrical Impedance Analysis Method among School Adolescents in Sokoto, North-Western Nigeria

Background: Excess body fat is recognized as a risk factor for cardiovascular diseases, diabetes mellitus and gallbladder diseases. Body mass index (BMI) being the most widely used method of obesity assessment does not differentiate between individuals whose weight is as a result of excess fat or excess muscle mass. This is significant because it is the amount of excess fat rather than mere excess weight that determines the health risks of obesity. Therefore, techniques such as bioelectrical impedance analysis (BIA) that estimate body fat assume more importance in this regard.

Aim: To determine the pattern of body fat and prevalence of obesity, using Leg to leg BIA technique among apparently healthy school adolescents in Sokoto, Nigeria.

Methodology: A cross sectional study involving 360 subjects (180 males, 180 females, age range 10-18 years) selected from 6 schools within Sokoto metropolis, by a multi-stage random sampling. Subject’s weights, heights and BIA were measured. Age and gender specific percentage body fat cut-off values according to McCarthy et al. were used to classify subjects as overweight or obese.

Results: The mean percentage body fat (%BF) values were 8.2±4.1% for the males and 20.0±6.8% for the females (P<0.001). Mean BMI of the subjects were 18.3±2.7kg/m2 for males, and 19.3±3.1 kg/m2 for the females (P=0.001). Steady increase in body fat (%BF) with age was observed among the females, with the %BF values also being higher in the females (P<0.001). Based on the BIA method, the prevalence rates for overweight and obesity were 2.5% and 1.7% respectively. With the BMI method however, the prevalence of overweight was 3.3% and 1.4% for obesity. Age 15 years had the highest number of obese subjects (33.3%) whereas; ages 16 and 18 years had the highest number of overweight subjects (22.2% each).

Conclusion: This study has demonstrated the feasibility of using leg-to-leg BIA in body fat assessment in children. It is therefore, recommended that BIA be widely used in clinical practice for obesity studies, because it is a simple and precise tool for body fat assessment in children and adolescents.