To evaluate the effectiveness of body mass index (BMI) and bioelectric impedance analysis (BIA) methods in determining body compositions in young male and female.

Body compositions of 335 female (Mean±SE: 15.2±0.05 yr) and 409 male (Mean age±SE: 15.6±0.05 yr) students aged between 14-18 (mean±SD: 15.1±0.6 yr) and 104 female (Mean±SE: 20.5±0.1 yr) and 409 male (Mean±SE: 21.1±0.1 yr) students aged between 19-23 were analysed using BMI and BIA methods.

In male subjects, aged between 14 to 18, normal body composition ranges determined using BMI 67.4% (n=303) and determined using BIA 20.0% (n=90) were significantly different (p < 0.05). A statistically significant difference for normal values was also observed in the group aged between 19-23 in male subjects: BMI 83.9% (n=256), and BIA 25.5% (n=78), (p < 0.05). In female subjects, in the group aged between 14-18, normal values for BMI 68.6% (n=230) and for BIA 51.3% (n=172), (p < 0.05).

In young subjects, BMI may result an invalid body composition analysis. BIA analysis may result more reliable body composition analysis, and it should be considered in clinical studies and public health.