Viren Swami, Ph.D. YouBeauty Attraction Expert replied over 1 year ago:
The thing about BMI is that it's a useful proxy for body fat, but the medical establishment have also acknowledged that it has its limitations. For example, BMI cut-offs have varied across time (when the normal/overweight cut-off was lowered in the US from BMI 27.8 to 25 in 1998, it meant about 25 million Americans who were previously 'healthy' were now considered 'overweight') and by culture (Southeast Asian populations, for example, have different cut-offs). It has also been suggested that BMI is less accurate for people who are lean or athletic (their higher muscle mass tends to put them in the overweight category). Neither does it fully account for a person's body frame, as you say. For example, a person could have a small frame and be carrying excess fat, but their BMI might suggest they are healthy; or, a person could have a large frame with very low body fat, but still be classified as 'overweight' according to BMI cut-offs. In order to get a better picture of body fat, medical professionals tends to use a number of measures in addition to BMI, such as skin-fold measurements, bioeletrical impedance analysis, and so on. All of these provide much better indicators of a person's body fat percentage than BMI.