Body Mass Index can be an unreliable measurement

Guest article by Laurie Beebe

Simply put, the body mass index measures the mass of your body. It does this with a calculation using your height and your weight; period. This means it does not take into account whether you are old or young, male or female, fit or fat, or whether you have a hormone imbalance. The number calculated after entering your height and weight is used to fit you into a category such as “normal weight”, “overweight”, “underweight”, or obese. But what if you are just “big-boned”? Should you pay attention to what the number says? Should you try to lose weight because your physician recommended you try to get yourself down to the more desirable category on the BMI chart?

Well, here’s the deal: Most of the time, people have a weight they’ve grown comfortable with and they don’t feel the need to fit into someone else’s ideal for their own body weight. But the suggested BMI values are based on health risks. Over years, health professionals and researchers repeatedly find that people who fall within “normal” BMI range (18.5 to 24.9) have fewer health problems. (This would be, as an example, someone who is 5 feet four inches tall and weighs 140 pounds). On the other hand, those who have a BMI below this level or above this level–particularly those who fall in the “obese range” (having a BMI of 30 or greater)–have exponentially more health problems. Health risks include chronic heart disease, hypertension, elevated cholesterol levels, high blood sugar, and joint problems. Even some forms of cancer have been linked to being overweight.

So, if you now trust that the ideal BMI range is truly the healthiest place to be, what about extenuating circumstances that falsely predict an increase in health risk for, say, body builders. People who lift weights and have extra muscle tissue weigh more, but that does not, in fact, put them at the same risk for chronic diseases. This is where BMI can be unreliable–it does not take into account someone who is healthy, but has a bit of excess weight because of more muscle tissue.

If you believe you are “falsely” placed into the “overweight” category and you aren’t really overfat, ask yourself this: “Are you a body builder?” No? How about a football player, wrestler, gymnast or someone who works doing very heavy manual labor and has extremely developed muscles? If the answer to all of these is “no” then you are really kidding yourself by trying to rationalize how overweight you aren’t! If you don’t make a habit of exercising five days a week, or are extremely active for work, then there’s a 95% chance you really are overfat and that’s why your BMI shows on the “overweight” range on the chart. If you show up with a BMI over 30, there’s little to save you except for admitting that you need to lose some weight. An example of someone in this range would be 5 feet 6 inches tall and weigh 190 pounds. There aren’t many healthcare professionals who could say you don’t have a few pounds to lose, no matter how much you believe you’re in “pretty good shape”!

Check out the free plug-in chart below to enter your height and weight and instantly see what your BMI is. Then, if the result is “overweight”, you’ll have to be the judge as to whether you are in fantastic shape (really?) or you actually need to seriously consider losing a few pounds to improve your long-term health.

Visit to find your BMI Find out more about healthy weight loss under the guidance of a registered dietitian at

2 thoughts on “Body Mass Index can be an unreliable measurement

  1. Really interesting and informative post! It makes me think about (and I don’t know what you think about this) how so often we/people tend to say “Oh I’m not overweight, I look fine”.

    But even if we look fine (some of us do “look fine” or even great) what about our health, underneath the surface and appearances? Heck, even when we fall into the healthy BMI categories, if we’re not exercizing and eating healthfully, there’s STILL a problem there!

    Anyway, my point is that it seems to me that in some ways we’ve gotten overly-focused, culturally, on appearances. Then in defense of our looks we ignore what’s more risky and dangerous: our poor health. Maybe ignoring the BMI results, for some of us, is related to this “Oh I look fine!” defensive denial?

  2. Clarabelle, You make some great points. I visited your website and I love it. Marked it in my favorites and I will be back to read more of what you have to say.

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