Body Mass Index

Your Body Mass Index and What It Says About Your Health

Most medical personnel will tell you that being overweight is unhealthy. A long list of ailments awaits those who are overweight or obese. These ailments include increased risks of high blood pressure, heart disease, stroke and diabetes. Yes, even as a young adult, you are at risk for these.

Have you ever stopped to think, however, that the word "overweight" means different things to different people?

For instance, a 5-foot-4 inch tall woman can be considered overweight at 160 pounds, while a 6-foot-2 inch man is on the thin side at 160 pounds. How do you know what's the ideal weight for you? One way is to put everything on the same scale by adjusting for height. This can be done using the Body Mass Index (BMI) calculation.

The BMI is used by doctors to assess patients as overweight or obese. It does a very good job of describing relative weight for any given height, and measures your overall total body fat content. It does not, however, differentiate between people with too much fat and athletic, muscular people. Thus, you should really use BMI in conjunction with other body-composition assessments.

The BMI is a more accurate measure of body fat than a height-weight table, but it does have some drawbacks. It actually overestimates body fat in people who are very muscular, such as bodybuilders, or those who have lost a lot of muscle mass, such as the elderly or ill. High BMIs in pregnant or breastfeeding women, or people under 5 feet, may also not reflect "fatness."

To manually calculate your Body Mass Index, or BMI, you must divide your body weight (in lbs.) by your height in inches squared, then multiply by 705. For example, if your weight were 200 lbs. and you were 5 feet tall, the calculation would look like this: 200 lbs. divided by 60 inches squared, or 3,600; then multiply by 705, or: 200 / 3600=0.055555... x 705 = 38.7. So the BMI would be 38.7.

A BMI between 18 and 25 is considered normal.
A BMI below 18 puts you "at risk" for being underweight--or you could be on the low end of the growth curve for your age, or very athletic.
A BMI over 25 means you are considered "at risk" of being overweight.
A BMI over 30 means you are considered overweight.

If you scored in the "normal" range, that's great! If you scored over 25 or 30, read Healthy Dieting and speak to your health-care provider. She is better able to evaluate if you are indeed overweight.