Obesity, BMI and stuff

[chickenfeet]

I'm overweight but not by much. I weigh 213 pounds which at just over 6 feet tall gives me a BMI of 28.5. I would like to be 200 pounds (BMI=26.7) which would apparently make me still overweight. Frankly this is nuts. I was 200 pounds when I was playing rugby competitively and was as fit as I've ever been in my life. It's not like I'm unfit now. I've run 25km in the last four days which is more than a lot of people do in a year. What's really scary is that according to the BMI calculation I could be 140 pounds and still be a healthy weight! When I was ill about ten years ago I dropped to 155 pounds and I looked horrible, all skin and bone, and not in the least healthy.

So let's look at this in the context of the "obesity epidemic". It's trivially obvious that the BMI statistic exaggerates obesity among tall people and does the opposite for short people (weight, other things being equal, is proportional to the cube of body weight rather than being linear). It's a fact that in the developed world average height has been increasing for at least a hundred years. This of course means that obesity statistics based on BMI will get worse even if nothing is happening! I'm not saying there isn't a problem but it is being exaggerated by the use of a very dubious statistic.

Comments

[adjectivegail]

It's trivially obvious that the BMI statistic exaggerates obesity among tall people and does the opposite for short people
I'm not sure I agree with this, but 1) I'm not any kind of a mathematician and 2) I'm short and fat so I guess I would disagree (I interpreted your sentence as '... and the obesity of short people is under-expressed by the BMI', feel free to tell me if I'm wrong). But. The BMI says that I need to lose a minimum of one quarter of my body weight in order to stop being overweight/obese and become 'normal'. Now, yes, I could stand to lose a fair bit of weight, but I don't think that much, and certainly not more! Even if it happened over a period of years, I would quite frankly be alarmed to lose that much weight. Basically I don't think the BMI is any more accurate for short people than than it is for tall people, that it is for especially athletic people - especially athletic women - than it is for... *waves arms* many different kinds of people. Mind you, I ranted about the BMI in my journal not that long ago, so I guess I would say that :)

[chickenfeet2003.livejournal.com]

What bugs me is that a fairly reputable body like the CDCP would use BMI as the basis for statistical reporting and policy goal setting when it is obviously a crap statistic. The only justification is that it is easy to gather.

[(Anonymous)]

Apparently the quick and dirty guidleline now is waist size, not BMI. If it's over 38 for a guy, you have trouble.