Criticism of BMI for Measuring Bodily Health
NPR posts an interesting article criticising the use of BMI to indicate obesity. This is relevant to this blog, since the Wii Fit uses BMI extensively to track obesity, or the lack thereof.
I can say with conviction that when I step on for the “Body Test” and the cutesie little voice says, “That’s obese!” I hate it with a passion. Nice to know that science bears out my aversion!
BMI, or Body Mass Index, is a mathematical formula that incorporates height, age and weight to determine whether one has a healthy physique or not. The higher the BMI, the greater the degree of obesity. The article points out that BMI is a formula developed 200 years ago as a short-hand to help the goverment of Belgium determine what percentage of their population is obese. But it fails to take into account people who are big and very fit – because muscle outweighs fat. In other words, a large man who has very little body fat would have the exact same BMI, indicating obesity, as a very fat man of similar size.
BMI is the default data point of the Wii Fit, though you can switch to pounds by clicking on a button. In my case, it’s actually an okay indicator – every obese person will have a high BMI, but not every person with a high BMI will necessarily be obese. For my part, though, it’s not excessive musculature that’s causing me grief.
Should I ever reach a very low body-fat percentage, and yet remain ripplingly buff, I suppose I’ll have to stop considering my BMI. In truth, I’m quite a bit more worried about my waist size than I am about pounds or BMI, but it’s much easier to track the trend on those numbers, which change more rapidly.
