Q. I’ve lost weight, and now my body mass index is in the normal range. Does this mean I’m healthier?
A. Yes and no. Shedding even a few pounds can reduce your risk of many serious conditions, including heart disease. But a normal BMI reading isn’t enough to say whether you’re healthy, simply because the numbers don’t tell the whole story. The measurement doesn’t distinguish between body fat, muscle, and bone, so it’s hard to know if "normal" people have the right ratio of those three things. Your score could mean you have good muscle and bone mass with low body fat — or you could have no muscle, porous bones, and lots of fat. The BMI can’t tell the difference: A skinny, weak person could be at high risk for osteoporosis, heart disease, cancer, and more.
"When your BMI is normal — between 20 and 30 — you need a second measure," says Francisco Lopez-Jimenez, MD, of the Mayo Clinic. A good one: measuring your waist to see how much fat you’re carrying. (Most home body-fat scales aren’t reliable.) If you wrap a tape measure at the level of your navel and the reading is more than 35 inches, your heart disease risk is above average. See your doctor for a cholesterol, blood pressure, and stress test and, if necessary, to discuss lifestyle changes and treatment options. You can also get more information about your risk by taking the American Heart Association’s Live and Learn quiz.
Originally published in MORE magazine, February 2007.