Some Body Mass Index Facts

What Does Your BMI Mean?Learn how your "body mass index" tips you off to health risks.by Sara Ryba, R.D., C.D.N.
The BMI (body mass index) is a general calculation used to help assess your body weight and risks for weight-related health problems.The BMI is a flexible guide and factors in a certain level of difference between individuals. Nevertheless, it is still a general tool – your specific body make-up ultimately determines your healthy weight range.One variable BMI fails to consider is lean body mass. A healthy, muscular individual with very low body fat still might be classified as "obese" using the BMI formula. Conversely, a thin person may fall within the healthy BMI range, but still have a percentage of body fat that is considered unhealthy.The following BMI ranges are guidelines, and are used to screen and monitor large populations to detect risk of weight-related disease. Use our BMI Calculator to determine your body mass index and what range you fall into.
Underweight
Less than 18.5
Healthy weight
18.5 to 24.9
Overweight
25.0 to 29.9
Obese
30 or higher
Other FactorsIn each individual, other data must be used to determine if a high BMI is associated with increased risk of disease and/or death. Your BMI alone is not diagnostic. After determining your score, here are a few of the other factors that may come into play.
If you are in the healthy weight range, consider your weight history. Has your BMI increased significantly over the past 2 - 5 years? If so, and it is not a result of increased weight training, this should raise a red flag, even if you are still within the healthy BMI range.
If you find yourself in the overweight range, but consider yourself lean and "in shape," you might be carrying a lot of weight in the form of muscle. And you may, in fact, be at a healthy weight.
There are other measurements, such as the waist-to-hip ratio and waist circumference, that can help you determine if you are carrying excess body fat in unhealthy places.
The Bottom Line on BMIGet to know your body. Learn what is healthy for you and discuss any concerns with your health care provider.