DnvrFox

Body Mass Index Slammed By Bicycling Magazine (partial quote from page 51, September, 2005):

Quote:

When you try to make the BMI work for cyclists, or football players, or anyone with a lot of muscle mass, it is not a very good indicator of fitness, says Conrad Ernest, director of the Center for Human Performance at the Cooper Institute in Dallas . . . .


A better idea. Realize that body types are in many ways preprogrammed . . . . It might be better to accept that genetic gift and work with it.

This sidebar gives several examples of the misapplication of the BMI.

Read it yourself!

cslone

I hate the BMI. I am 6'1", muscular, but according to BMI, overweight.

sjjone

BMI sucks for everyone. It does no favors for non-athletes as they are lulled into false security. On the female side, consider my 5'9" 130 lb friend-BMI of 19. She can wear a size 4, but her body fat % is around 30% if not higher. I'm 5'7", 140, still a normal BMI, but with 20% body fat.

I train hard and eat well-I'm healthier and at less risk for future health issues-BMI is totally irrelevant IMO.

grgs

The thing that sucks about BMI is that it's usually presented as being something new and scientific, but it's nothing more than those old height-weight charts. Stupid.

G-Unit

BMI has been B.S. ever since they came out with it... Evander Holyfield (back when he was heavyweight champion) was considered obese according to the BMI.

ed073

BMI is the stoopiest measure of someone's morphology ever.

I dunno why it keeps getting mentioned in the media, etc. It's so out of date to be irrelevant.

Makes ed mad....

SSP

The sidebar seems to be implying that cyclists have "a lot of muscle mass"...what's up with that? Have they been to a century ride recently? I would guess that the average avid cyclist is well down on the BMI scale - at least, most of the ones I know are. Cycling efficiency is mostly about power to weight ratio, and BMI is a reasonable surrogate measurement for that for most people (assuming a reasonable amount of fitness).

Of course, as the sidebar points out, BMI says nothing about "fitness" - it's just a simple way of describing how relatively heavy or light a person is, compared to their height. You can certainly be very "fit" with a high BMI. And, you can even have a low body fat with a high BMI (if you're bulging with muscles). But, you won't be a very efficient cyclist with a high BMI. You'll either be carrying excess fat, or excess muscle - both of which will slow you down on the bike.

SSP

It keeps getting mentioned because it's used in many scientific studies, and appears to be related to increased risk of mortality. It's not "irrelevant" to the many scientists who study these issues.

For instance, the New England Journal of Medicine published a study in October, '99 in which one million subjects were tracked over 14 years. They found a direct correlation between increasing BMI's and increased risk of mortality. Specifically, they found:

The risk of death from all causes, cardiovascular disease, cancer, or other diseases increases throughout the range of moderate and severe overweight for both men and women in all age groups.

In healthy people who had never smoked, the nadir of the curve for body-mass index and mortality was found at a body-mass index of 23.5 to 24.9 in men and 22.0 to 23.4 in women.

Pat

Actually, this conclusion is coming under increased scrutiney. I have read that most of the increase of mortality with obesity occurs 1) at the really obese levels and 2) is caused by cardio problems. With the new treatments for cardiovascular disease, the rates of death from cardiovascular disease are far lower and the negative effects of obesity are lower. Of course, risk from cardio vascular disease is not about weight per se, it is more about diet. There probably is some correlation between diet and BMI but it is not that big a thing.

Interestingly enough, recent studies seem to show that active and mildly over weight people are healthier than inactive skinny people.

The recent studies seem to show that there is no simple correlation between health risk and BMI. There is an increase in health risk if one is morbidly obese.

Another problem with BMI is that muscular, fit and relatively lean people can test out as being "obese" on the BMI. Some people, especially body builders can be very lean such as 4% body fat and still considered "obese" by the BMI. It really does not make any sense.

kuan

What is that, good or bad? What does nadir mean?

SSP

"Nadir" means the low point on the curve of mortality risk. Thus, those BMI levels were associated with the lowest risks of mortality.

SSP

I agree that more research needs to be done, and that there probably are many extenuating factors. I'm also aware that some of the more recent research seems to show that "mildly overweight, but fit" people are at very little increased risk.

But, the correlations between health risk and BMI are still there...clearly it's much better if you're active instead of sedentary, but if you're at BMI > 30, you're probably at increased risk regardless.

Re: "fit but fat", some studies in women have shown that "fitness" confers protection against things like cardiovascular disease, but does not protect against other diseases (e.g., cancers) that are associated with "fatness".

As for "highly muscular" people with high BMI's (the NFL linebackers) - this comes up a lot in these discussions. But: a) they are a tiny percentage of the population, b) I'm unaware of any research indicating that their health risks are lower (it seems like they should be at decreased risk, but I've not seen any evidence to that fact, and NFL linebackers seem to die pretty early).