Overweight in trained subjects - are we looking at wrong numbers? (Body mass index compared with body fat percentage in estimating overweight in athletes.).

Body mass index (BMI) is widely used as an index of obesity in adults. In trained population, individual with low body fat could be classified as overweight by BMI. To evaluate this problem, the purposes of this study were to determine the BMI and body fat percentage (BF%) of trained and untrained subjects and to evaluate the accuracy of BMI classification (> or =25 kg.m(-2)) as a prediction of overweight/obesity in trained subjects. The total number of 299 trained (basketball players) and 179 untrained male subjects participated in this study. Body height and body mass were measured; BMI was calculated for all subjects. BF% was determined via Tanita bioimpedance body composition analyzer. BMI >or = 25 kg.m(-2) and BF% > 20% were used to define overweight. There was no significant age differences. Body mass, height (p < 0.01) and BMI (p < 0.05) were significantly higher, although BF% was significantly lower (p < 0.01) in trained group when compared to untrained. Eighty-five trained subjects had a BMI of 25 or higher, indicating overweight. Of these, only three individuls had excess BF%. The results of the present study suggest that a BMI > or = 25 kg.m(-2) is not an accurate predictor of overweight in trained subjects.