Yesterday, there was an article on BBC News about being fat and fit. Great! Some mainstream traction for this important issue. In a nutshell, the article says that your “metabolic fitness” is more important that your weight. Metabolic fitness means that your blood pressure, cholesterol, and blood sugar are normal, and that you exercise.

Of course, some people disbelieve this idea of “fit but fat.” They claim that any amount of excess weight is a death sentence. I think that most of these people are themselves naturally thin, and disguise fat bias under the guise of being concerned about the health of fat people like me. Thanks, but I’m fine. My resting heart rate is below 60, my blood pressure is low, and my blood sugar is excellent. I typically work out five days a week. I’m metabolically fit, no matter what the scale says.

While I applaud the BBC article, I take issue with this quote at the end, from a woman representing the British Heart Foundation: “But don’t get too caught up on the numbers on the scale. Calculating your body mass index and measuring your waist are great ways to keep on track.”

Ah, BMI. what is it? What does it mean? Does it matter? BMI is a formula that takes your body mass (weight) and divides it by your height. Once you know that number, you can then see what category you fall into, which includes underweight, normal, overweight, and obese. The categories further break down from there, so you can find out if you are considered moderately, severely, or very severely obese. Handy information, right?

Wrong. BMI doesn’t consider what part of your body is fat versus lean tissue/muscle. Based on BMI alone, many professional athletes and Olympians are overweight and obese. Crazy, right? BMI doesn’t know that these people are mostly muscle, and it doesn’t care.

To learn more about why BMI is not a good indicator of your health, check out this article from NPR. It includes this gem: “The person who dreamed up the BMI said explicitly that it could not and should not be used to indicate the level of fatness in an individual.”

Here’s the bottom line: The scale and your BMI do not dictate your level of health, any more than the size of your pants. Want to know if you’re living a healthy, well-balanced life? Find out what your cholesterol and blood pressure are, and monitor them. Get your blood sugar tested. Move your body, and fuel it well. These are the measurements that matter.