BMI

Here’s an article I came across awhile back: Normal Weight Obesity: An Emerging Risk Factor For Heart And Metabolic Problems

More than half of American adults considered to have normal body weight in America have high body fat percentages — greater than 20 percent for men and 30 percent for women — as well as heart and metabolic disturbances, new Mayo Clinic research shows. The finding conflicts with the widely held belief that maintaining a normal weight automatically guards against disorders such as high levels of circulating blood fats and a tendency to develop metabolic syndrome, which often leads to type 2 diabetes.

First, some history on the Body Mass Index. It was devised in the 1800s by Adolphe Quetelet as the “Quetelet Index of Obesity”. In the 1980s, it became the international standard for comparing weight against an objective standard. It is the measurement the Mayo Clinic researchers used in the above study. To calculate your BMI, divide your weight in kilograms by your height in meters, squared. The BMI was devised “as a simple means of classifying sedentary (physically inactive) individuals with an average body composition.”(2) Note that it was not devised as a one-size-fits-all measurement. It was designed for one very specific population and has now been put into use for everyone.

But we have to ask, “what is a normal weight?” According to the BMI, I’m supposed to be between 144 and 175 lbs (3), yet I can’t recall when I weighed less than 180 lbs and I’m currently sitting around 185 (BMI of 26.5), where I’ve been for the past few years. Given that few people would guess that I weigh that much and that I maintain a low body fat percentage, I find it laughable to think that I’m “overweight,” but that’s what a measurement based solely on weight compared to height will give you. I can only imagine what I’d look like at 144 lbs or even 160 lbs. The very upper limit of that “healthy” range may be doable if I were willing to sacrifice some muscle. So should I strive to be “normal” or stay at the weight my body naturally gravitates to when I don’t try to alter it by adding or losing mass?

So once you’ve calculated your BMI, what should you do with it? Throw it away. It’s useless. Go stand in front of a mirror and jump. Do things jiggle that you’d rather not have jiggling? Do your clothes fit the way you want them to? Do you have the muscle definition you’d like to have? Those should be your measurements, not what the scale says. If you fit into your college jeans, which seems to be a female marker, why does it matter what the scale says?

Here’s an amusing thought: most every NFL linebacker is categorized as obese, as are most other professional athletes. Obese like Bill Romanowski and Junior Seau. Many elderly folks with very little muscle mass qualify as “healthy weight”. Those are the skinny-fat folks that the article above references and it doesn’t affect only the elderly.

There’s truly too much focus on weight in our culture, especially by women. That’s the problem with the BMI, it focuses solely on weight versus height. It doesn’t take into account muscle mass, waist circumference, or body fat percentage. Thinking about “normal weight” made me think of a post Alwyn Cosgrove had some time ago called “The Fat Sucking Machine” (4):

If we had a magic fat loss machine — that you stepped in and pushed a button and you came out looking EXACTLY how you’ve always dreamed of looking and feeling - the exact dress or pant size you wanted, with the definition and muscle tone you want, at the bodyfat percentage you want - you can see your abs (if that’s what you want) etc etc.

Would you be interested? Of course you would!!

But what if the side effect of the fat loss machine is that it increased bone density and muscle density by 100%. So while you looked and felt better than you’ve ever felt before — the scale is 50lbs higher than it’s ever been. So for example a 150lb-er would come out looking amazing, but weighing 200lbs…

So what is the value of the BMI? On an individual level, absolutely none. It is a statistical tool which only holds a small value and that is for use across a large population, so that the heavily muscled athletes with BMIs of 28+ are averaged out by the skinny fat people that have the aforementioned BMIs of 18-25 with body fat percentages of 25%. If weight is what you’re concerned about, I have the perfect solution for you. Cut off your leg. You just lost a good 1/5 of your body weight. Are you satisfied? Most of the time, weight loss attempts result in a smaller version of the same body, twenty pounds lighter, but still looking like a pear.

So what are better measurements to check? Body fat percentage is a great start. For men, a normal range is in the mid-teens. For women, low- to mid-20s. Women get the pleasure of carrying more fat for nourishing those growing babies. Obviously athletes will be at lower percentages, but for the average person, those are good ranges. Waist circumference, or better yet, waist-hip ratio is another one that can help determine what kind of weight you’re carrying. The easiest measurement though is the mirror test. Look in the mirror. Jump up and down. Do you like what you see? Are your clothes fitting better or worse than they did last week? If the answer is “better,” then keep on keeping on. If the answer is “worse,” go back to the drawing board.

Sources:
(1) The History of BMI
(2) Body Mass Index
(3) Tables of normal weight for height (1958)
(4) The Fat sucking machine…


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