The medical establishment has generally acknowledged some shortcomings of BMI.[12] Because the BMI is dependent only upon net weight and height, it makes simplistic assumptions about distribution of muscle and bone mass, and thus may overestimate adiposity on those with more lean body mass (e.g. athletes) while underestimating adiposity on those with less lean body mass (e.g. the elderly).
In fact, some argue that the error in the BMI is significant and so pervasive that it is not generally useful in evaluation of health.[13] Due to these limitations, body composition for athletes is often better calculated using measures of body fat, as determined by such techniques as skinfold measurements or underwater weighing.