Monday, July 6, 2009

Is the BMI a hoax?

I just came across this article on that gives 10 reasons why using the BMI formula is wrong. I've always known that those who are really athletic end up with skewed BMIs, but it gives compelling reasons why we need to abandon the system completely and look at other things like waist size. I don't think I count as really athletic, but I've often wondered if at 5'3" and between 135-140 lbs if I'm really borderline overweight. Could I lose a few more pounds? Probably. Am I truly overweight? I don't know. Perspective tells me no, since so many people around me are much larger than I am. I want to say that most Americans are overweight, but now that we're questioning the BMI that assumption is invalid.

Can we truly measure ourselves against one another by some mathematical formula? I don't think so. In the end I think we should focus on being in shape and healthy, not trying to hit some magical number based on height and weight.


Jennifer Liang said...

Honestly, I think I agree with you on this one. The amount of weight Jimmy would have to lose to be within a healthy BMI is astounding. But he's mostly muscle!

Illbay said...

I am a 54 year old male, 5'-9.5" and until recently weighed 272. I have since begun Jenny Craig and am in my fourth week. It's going well; after the initial couple of weeks the hunger pangs have gone and I'm adjusting well to the 1,700 Calorie per day diet. I'm now at 266.

According to the brain-dead BMI chart I must lose down to 169!

I bought a Tanita scale with body-fat percentage measurement. It says I'm at 37% body fat, and I want to get down to 15% which is well within the "fitness" category. If I do the calculation where Wi and Bi are initial weight and fat content respectively, and Wo and Bo are desired weight and fat content, then

Wo = Wi*[(1-Bi)/(1-Bo)]

For me that is

Wo = 266 * [(1 - 0.37)/(1 - 0.15)] = 197 Lbs.!

Losing down to 169 would be a body fat content of

LW = 266 * (1 - 0.37) = 167 Lbs (Lean Weight, weight of everything inside me that's NOT fat)

Bo = (169 - 167)/169 * 100% = 1.2%!!!

I would essentially be in a coma!

So my goal is suddenly 28 pounds closer, and I won't be wondering why I keep falling down all the time.

The "government recommended weight chart" is pretty much useless, like 80% of the stuff our government does *for* us! My reading indicates BMI is appropriate for large populations as a trend measurement, but is not applicable for individuals. !