In common usage, "obese" means "very overweight," and often carries negative connotations. But in weight-control medicine, "obese" is a non-judgmental term that simply expresses as a number--a certain body mass index.

Body mass index (BMI) has been the medical standard for obesity measurement since the early 1980's. Government researchers developed it to take height into account in weight measurement. For example, let's say someone weighs 150 pounds. Is he or she obese?

That's impossible to say without knowing the person's height. The answers would be different for some who is 5' 0" tall, 5" 4", and 5' 11".


Recommended BMI's are in the range of 20 to 26.

The "overweight" range is 26 to 27.3 for women, 26 to 27.8 for men, though some authorities peg the upper limit of overweight at a BMI of 30.

Most authorities say that "obesity" begins at BMI's above 27.3 for women and 27.87 for men. All authorities agree that anyone with a BMI over 30 is obese.

According to these conventions, the woman who is 5' 0" and weighs 155, has a BMI of 30.14, and is obese.

Someone who is 5' 4" and weighs 155 has a BMI of 26.6, and is overweight, but not obese.

Someone who is 5' 11" and weighs 155 is in the healthy BMI range.