I will come of a critical here, so be it. And sometimes this applies to me as well.

 

A lot of people are overweight because they never deny themselves anything, and many of these same people will not make themselves uncomfortable with a bit of exercise. I notice at work....the overweight people seldom take the stairs.

 

It is very much a lifestyle choice. I remember many years ago when I was still playing soccer, and I was playing in an indoor tournament. We had just enough players to field a team, and I was playing defense and midfield at the same time. There was a lady on defense with me who was chubby...not meaning it critically...but she couldn't cover a lot of the field on a good day. However, between games she complained of being hungry, which we all were after two games already that night, and she goes and gets a quarter-pounder, large fries and soda to wolf down before the last game. I knew she would have to pretty much stand in place the last game, and it struck me how people cannot deal with a little hunger. A healthy snack would have been one thing. It was a rough last game.

 

The BMI is useless BTW.

 

BMI has it's flaws but it certainly isn't useless. It has good specificity i.e. if your BMI says you're obese you're very likely obese (true positives) however, it's lacking in sensitivity i.e. you may actually be obese even if your BMI doesn't say you are (false negative). Therefore, an analysis using BMI to calculate percentage of the population that is obese is actually incredibly accurate.

 

Accuracy of Body Mass Index to Diagnose Obesity In the US Adult Population

BMI has it's flaws but it certainly isn't useless. It has good specificity i.e. if your BMI says you're obese you're very likely obese (true positives) however, it's lacking in sensitivity i.e. you may actually be obese even if your BMI doesn't say you are (false negative). Therefore, an analysis using BMI to calculate percentage of the population that is obese is actually incredibly accurate.

 

Accuracy of Body Mass Index to Diagnose Obesity In the US Adult Population

 

I am approaching it unscientifically. But when I am in shape....I'm not quite there right now... I am tall and lean, and my BMI says I am overweight. I do not believe it accounts for lean muscle mass...at least when I have seen it applied at health events.

I am approaching it unscientifically. But when I am in shape....I'm not quite there right now... I am tall and lean, and my BMI says I am overweight. I do not believe it accounts for lean muscle mass...at least when I have seen it applied at health events.

 

With respect to the overweight vs normal cut off those numbers are likely very different. I haven't personally seen any studies on that so I can't say for certain but I'd guess BMI probably is much less accurate at that threshold. However, for calculating obesity it is much more accurate which is what the study I posted above was looking at.

I am approaching it unscientifically. But when I am in shape....I'm not quite there right now... I am tall and lean, and my BMI says I am overweight. I do not believe it accounts for lean muscle mass...at least when I have seen it applied at health events.

 

When I was in the best shape of my life 10 years ago, I was lean and muscular, with about 9-10% body fat. I had to fight to get a better rate on a life insurance policy because my BMI had me classified as obese. Of course now, with age and less visits (ok no visits) to the gym, my BMI is pretty accurate. BMI definitely doesn't work for muscular folks, but I don't think the vast majority of our population fits into the muscular category. For the average person, BMI probably is a pretty good indicator.

With respect to the overweight vs normal cut off those numbers are likely very different. I haven't personally seen any studies on that so I can't say for certain but I'd guess BMI probably is much less accurate at that threshold. However, for calculating obesity it is much more accurate which is what the study I posted above was looking at.

 

Agreed...it's like most measurements...it's hard to find a perfect one that fit's all scenarios. However, the risk is as @rjs4470 mentions, that someone accepts this as a universal measurement and penalizes a person that is actually fit.

'Anyone who completely dismisses BMI as useless is just not very educated on the subject. No BMI does not work for a 5'9" 200lb guy with 5% body fat. But it is a lot more accurate for the average Joe than most want to admit. I'm not saying it be used in the example @rjs4470 laid out, to penalize people but it definitely can be used has a tool like the article used it.