April 9, 2009

Muscularity

Here's a press release about an article in the British Journal of Nutrition entitled "BMI Not an An Accurate Obesity Measurement:
“This [Body-Mass Index] scale was created years ago and is based on Caucasian men and women,” says Bray, “It doesn’t take into account differences in body composition between genders, race/ethnicity groups, and across the lifespan.”

In the current study, ... researchers used dual-energy x-ray absorptiometry, which is a low dose x-ray known as DXA, to determine percent fat. DXA can be used to estimate bone density, lean mass and fat mass.

When the two results were compared, researchers found that the DXA estimate of percent fat of African American women was 1.76 percent lower for the same BMI compared to non-Hispanic white women. Since BMI is assumed to represent body fatness, an African American woman would not be considered overweight or obese until she reached a higher number than what is indicated by the current BMI standards. The opposite is the case for Hispanic, Asian and Asian-Indian woman. Their percent fat is higher by 1.65 percent, 2.65 percent and 5.98 percent, respectively. So they would be considered overweight or obese at amounts lower than what the BMI standards indicates. The results for men were similar.

“Right now non-Hispanic white women are not considered obese until they have a BMI of 30 or above. Based on our data in young adults, for Hispanic women the number would be around 28,” says Bray. “For African American women the number to cross is around 32."

Bone mineral content, hydration state, and the density of lean mass found in different ethnic groups are some factors that account for the differences.

I pointed all this out in "Is Love Colorblind" in 1997.

My published articles are archived at iSteve.com -- Steve Sailer

28 comments:

ironrailsironweights said...

For men, it's very easy: if your waistline does not exceed the lesser of (a) one-half your height, or (b) 35 inches, you are not overweight, no matter what the scale says or what your BMI may be.

Peter

Anonymous said...

Male corset, activate?

Anonymous said...

I have always felt the fact that BMI does not distinguish between men and women to be absolutely and inexplicable bogus.

I'm a short guy -- 5'2". In high school (and now, actually) I weighed 150 lbs, which put my BMI at 27.4, smack in the middle of the "Overweight" category. Yet I was a varsity gymnast, and I wasn't carrying a whole lot of body fat. (I wasn't grotesquely muscular like a bodybuilder either -- I'm just broad in the shoulders, it's my natural build).

My girlfriend at the time was exactly my height. She weighed 93 lbs, which gave her a BMI of 17, significantly "Underweight." Yet she was healthy, ate well, and had a figure.

The thing is, if she had gone up to my weight, she would have been a porker. If I had gone down to her weight I would have been at death's door! So how can it possibly be sensible to use the same index for both of us???

Anonymous said...

The BMI assumes we are all vegetarians who go on long walks. In other words, the BMI was developed by Baby Boomer SWPLs fresh off their half-marathons. This is too bad, because there's actually nothing worse for the modern human than conditioning your body to build low energy, slow-twitch muscle fiber and store up lots of fat for a long week of foraging.

--Senor Doug

Shawn said...

Thanks for your famous "Is Love Colorblind" article, Steve.

Captain Jack Aubrey said...

So how can it possibly be sensible to use the same index for both of us???

Hatefact Alert!!! Hatefact Alert!!!

rob said...

Did anyone ever take body composition measurements and actually see how well c*m/h^2 correlated with bodyfat?

Granted, people who don't work out typically don't have much muscle, but some people do. It should include waist and hip measurements as well

ben tillman said...

Here's a press release about an article in the British Journal of Nutrition entitled "BMI Not an An Accurate Obesity Measurement:

Ya think???

Anonymous said...

Mathematically a more accurate measure would be weight/height^3, beacuse we are talking about 3-dimensional objects. This is why
IBM = weight/height^2 is very bad measure when height is close to 2 meters and above. Maybe before the calculators the doctors decided that height^3 was too damn difficult people to calculate :)

-The first anonymous

Pia J said...

"The thing is, if she had gone up to my weight, she would have been a porker. If I had gone down to her weight I would have been at death's door! So how can it possibly be sensible to use the same index for both of us???"

I didn't realize the same BMI index was being used for males and females. Apart from muscularity, I think frame size should also be taken into account. I'm a shorter female with an unusual medium frame which means I should weigh more than a finer boned female my same height. Muscularity doesn't factor into the equation for me because I have to do a tremendous amount of certain exercises to build up anything but my calf muscles. Nevertheless I'm also unhealthy at 93 lbs dead at much lower.

I find the differences in threshold for obesity somewhat laughable these days however. Obesity well over the minimum BMI for whatever race or gender is rampant these days. To my chagrin, I've discovered that demonstrating an interest in dieting for whatever purpose can be construed as being hateful to the overweight. What's worse to my thinking is the trend towards treating obesity as a sort of disability giving the obese protected status.

Many overweight people insist they can't control their weight; not much can be done about it therefore any bad consequences can't be avoided by effort. Having a similar tendency to put on weight, I can't help but see this as a grey area. I was morbidly obese in childhood and spent several years working out diet and exercise levels that would keep my weight close to normal. Yet there are people who would insist that I'm just genetically resistant to becoming obese, negating all my personal effort and in the process any evidence that it's possible to change your body by changing your eating habits and/or increasing your activity level.

Many of these people are also hypersensitive about weight issues to the point of making themselves martyrs. It's gotten so bad that I've been subjected to an unofficial program of reeducation concerning my supposedly toxic attitudes towards obese people. And in the process, those who can't or rather won't keep their weight down to healthier levels, have gained the power to damage my reputation because they don't like my theories. I can't believe overeating has become yet another source of victimhood and a tool for marginalizing those who don't accept whatever the currently obese insist the rest of us believe about the efficacy of dieting. I've even had strangers react to me as if I'm a Nazi insisting that everyone be height/weight proportionate or else be brutalized.

If I were in the dating market the polarization forced on me by such do-gooders would pose a further problem b/c I actually prefer guys who are hovering around the upper end of suggested BMI. The circumstances of my life are being dictated by people who represent my opinions in an extreme form which makes it easier to vilify me. Recently, I've had people suggest I lose weight to conform to my supposed Nazi ideals when in fact I diet to avoid diabetes and the back and knee problems I get when over a certain set point for me not to look good in a bikini. In actuality, I'm fine with bigger boned people who naturally carry more weight as I am with people like myself who maintain rounder outlines so to speak. I even prefer heavier guys to those who are naturally thin but my preferences and actual attitudes don't matter anymore. All that matters is what a group of people who are professional offense-takers say I think and believe. How can this be? How can it have gotten so bad that the "public" could even mischaracterize my true feelings to the extent the kind of guy I'm physically attracted to would think I found him repulsive. No offense, Peter, but I'm less likely to be attracted to a guy with washboard abs. I think my ideal guy is more a mesomorph on the verge of endomorphy lacking any other way to describe it.

I'm very angry about this and so not inclined to empathize further with the morbidly obese who have not only given themselves the right to dictate what I can think about weight issues but to retaliate against me for not conforming. I don't understand why they can't simply live according to their obviously different set of priorities regarding health and let the rest of us be. This has gotten way beyond the bounds of what should be legal regarding my right to privacy, btw. I don't know how much more sensitivity training in the form of abuse and denial of my civil liberties I can endure. And I can assure you, I'm less not more sensitive to others as a consequence of the treatment I've received. Why does it have to be so hard for people with different brains, different body types and different priorities to live together? I could've sworn we were doing a better job of it in decades past without half trying.

Evil Sandmich said...

African American woman would not be considered overweight or obese until she reached a higher number than what is indicated by the current BMI standards.

Judging by what I see when I go to the local mall one would not need to whip out a calculator to be able judge obesity in non-Egyptian African American women.

bbartlog said...

BMI sucks. Just because academics choose to publish endless papers using it (because the needed statistics are dead easy to acquire), doesn't mean anyone should take it seriously as a measure of health.
ironrailsandweights' heuristic is better than BMI, though in my opinion it gives a little too much leeway to young, short and/or slim men; if I (at 66" tall) let my waist grow to 33", I'd be at least a little overweight.

Sideways said...

Yeah, BMI is pretty useless if your build isn't average. I'm tall and sturdily built, and if you sucked every ounce of fat out of my body I'd have a BMI of 30.

My wife is of average height and has a healthy body fat percentage, but her family's bone structure is so thin she comes in at just under 17 (of course, she's Chinese, so Steve's post explains a part of that)

The two of us are sexually dimorphic to an almost absurd degree.

Anonymous said...

So would that mean in terms of muscularity, black > white > Hispanic > Asian > Indian?

Reticent Man said...

Yeah BMI is a too simplified to be useful. It just can't handle the range of human body types.

I'm short with broad shoulders and hips like Anon Gymnast and my BMI is way off. At my supposedly normal BMI weight I'd need to be hospitalized.

To add to that, people with builds like mine also fool the eye as to weight. I'm in decent but not great shape, white, 5'5 163 but people regularly guess 140-145. I have some asian buddies an inch or two taller you'd swear were the same weight as me if we stood side by side and I have them by 20 pounds. And it's not just muscle, I don't lift and I'm not overly strong.

My 6'2 cousin with obviously the same genetic build is in only slightly worse shape, and iirc he weighs 240 but I'd guess 210.

The bad news is these builds are probably worse for the heart. I'm guessing lighter people live longer.

Ronduck said...

The opposite is the case for Hispanic, Asian and Asian-Indian woman. Their percent fat is higher by 1.65 percent, 2.65 percent and 5.98 percent, respectively. So they would be considered overweight or obese at amounts lower than what the BMI standards indicates. The results for men were similar.

I knew a south asian girl back in HS and she was rail thin. She used to say "I'm not anorexic!" when others made comments about her low weight.

dearieme said...

Don't people classed as "overweight" outlive the "healthy", the "underweight" and the "obese"? In other words, isn't BMI as a guide to health bogus anyway?

(P.S. I speak as someone who's lost 5 lbs lately. At last!)

Anonymous said...

I've always been skeptical of BMI. In addition to its failure to take body composition into account, the same BMI for a tall and a short person describes very different body shapes/types because BMI is on a squared scale and we are three-dimensional beings (cubed). E.g.: Take a short man, 5'5" (1.65m) 149.7 lbs. (68.06kg), 12% body fat, and a tall man, 6'4" (1.93m), 204.8 lbs. (93.1kg), 12% body fat. Both have a BMI of 25. However, if the short man were 6'4" and kept the same body proportions (breadth and depth relative to height), be would weigh 108.9kg (239.6 lbs.). Conversely, if the tall man remained proportional and were only 5'5", he would weigh 58.2kg (128 lbs.). Even Shaquille O'Neal, who is consided huge at 7'1", 325 lbs. - 2.16m, 147.4kg (per nba.com), would only weigh 181.5 lbs. if he were 5'10" and remained proportional, which is hardly a big/stocky man.

Jun said...

"...dual-energy x-ray absorptiometry..."

Sorry, but the name of this x-ray technique made me giggle. Sounds like something out of a cheap, 1950s science-fiction movie. Or Flash Gordon or something:

As Ming the Merciless approached, Flash turned to Dale and said, "Quick! Hand me my dual-energy x-ray absorptiometry ray gun!"

:-P

Anonymous said...

"Don't people classed as "overweight" outlive the "healthy", the "underweight" and the "obese"?"

I don't know, but I have read that smokers who are overweight but not obese outlive smokers who are underweight or even at "healthy" weight.

Stopped Clock said...

There's a website that's been online for 8 years or so with little change which provides what I think is a somewhat more sensible alternative to the BMI:

http://halls.md/body-mass-index/av.htm

I'm another one of the short, broad types, and while officially I am overweight by a BMI calculator, I can just look in the mirror and see that I'm not.

Captain Jack Aubrey said...

while officially I am overweight by a BMI calculator, I can just look in the mirror and see that I'm not.

You are obviously a man.

Don't people classed as "overweight" outlive the "healthy", the "underweight" and the "obese"?

I did see a study that showed that people slightly overweight outlived those who were at their ideal weight. A little extra fat is good for the body when disease or illness comes along. I find it entirely believable, but I couldn't find the study via Google.

Mathematically a more accurate measure would be weight/height^3, beacuse we are talking about 3-dimensional objects.

One of those dimensions, thickness, correlates strongly with obesity and a second (width) correlates somewhat, so you'd be saying "well this guy weighs 350 pounds but he's 26 inches thick at the waist so that's not a problem."

Maybe before the calculators the doctors decided that height^3 was too damn difficult people to calculate

The formula for BMI was clearly designed with a calculator in mind.

Gc said...

Captain Jack, look, let`s say that we have a an 3-dimensional object 1*2*3 and let`s say it growths 10 percent and _it preserves it shape_. So we have an object of an volume 6.6 = 1.032..* 2.064...* 3.096...Now notice that the in order to preserve the shape the change must happen in all spatial dimension. If the 10 percent change happens only in two dimensions, it is obvious that the shape of the object must change.

bbartlog said...

Don't people classed as "overweight" outlive the "healthy", the "underweight" and the "obese"?

It depends on which population you are looking at. Yes, sometimes. For example, here is a study of 80-year olds in Japan; the main takeaway is that being underweight is terribly bad for you if you're elderly, but they also found that being slightly 'overweight' resulted in lower mortality than normal weight in some categories (and I believe overall). I know I've seen other, similar results for elderly populations.
There are a number of possible explanations; for starter, people who live to be 80 years old are not likely to be suffering from severe metabolic syndrome, so the risks they face are not the same as those of a typical 40 year old. Second, I believe that optimal weight probably increases somewhat as you get older; I doubt that our tendency to gain weight as we age is just an artifact.

Epicurean said...

The medical establishment again shines as such a beacon of academic honesty when it promotes BMI, while at the same time ruling that IQ is useless and "fascist".

Roger Chaillet said...

A family member is an MD.

He said each pound of weight loss is good for about 1 point of blood pressure.

So, lose 10 pounds, blood pressure drops 10 points.

The key is to not focus so much on BMI, but rather on blood pressure, cholesterol level, blood sugar, etc.

An eater said...

"The key is to not focus so much on BMI, but rather on blood pressure, cholesterol level, blood sugar, etc."

I agree wholeheartedly, Roger. However, I'm pretty certain there's another dimension to the BMI chart that includes body type. This explains why I know that my wrist and ankle circumference make me a mesomorph with a higher optimal weight than an ectomorph my same height. When determining optimal weight for more athletic types, measures of body fat should come into play.

More accurate methods for deciding whether or not someone is fit already exist but somehow the information isn't properly presented to the general public. Someday, simplified versions of what was originally good advice may end up being seen as much a threat to public health as bad habits.

Anonymous said...

"The bad news is these builds are probably worse for the heart. I'm guessing lighter people live longer."

Not if you kill them in hand to hand combat.