A limitation of BMI is that the relationship isn’t consistent for populations across the world, particularly in Asia.
In Singapore,
In India,
The measurements were taken of the average 19th century individual. Have you seen pictures of the average person in the 19th century? Underfed and malnourished was common, and is still common in much of the world, with a life expectancy in the 40s.
My thought would be the diet that causes the person’s weight. A healthy diet leading to a higher BMI would result in a healthier person than a bad diet that leads to a lower BMI. Also, studies have found that people who yo-yo diet, or who diet poorly in efforts to keep their weight down, damage their health significantly, as found in those studies that people with low BMIs had more health problems than people with higher BMIs.
BMIs are used by the insurance industry to raise rates on policyholders and deny coverage to otherwise healthy individuals. It is a method they use to cut their costs. It is not a scientifically-tested method, and should not be used in medicine at all. A fat measurement test, combined with cholesterol, blood pressure, heart and other tests, while certainly costing more, would be highly accurate and more effective gauges of one’s health.
As noted, muscle weighs much more than fat. Some people muscle heavily (without steroids), some don’t. Some are marathoners, some are not. You cannot compare everyone on one chart.
Actually, if you had read the material in the column, you would see that:
It IS scientifically tested, and
They have tried to update it with newer studies and always find out that the old formula remains as accurate as anything else of similar concept.
Why on earth would they want to do that???
This was one of the worst Straightdope Columns ever.
Everyone knows that the BMI index is completely defective.
The reason is that it is based on the square function of height.
Vis this fourmula: Weight*703/Height^2
Any idiot who passed high school physics knows that Weight
is a cube function of Height. Apparently medical professionals
arent required to know much about basic physics or math.
This is why Basketball players always end up with excessively
high BMI scores, they’re too tall. C’mon Cecil, big mistake here,
time to set the record straight.
Here is a website that describes a more reasonable formula for BMI
http://www.mines.edu/~gmurray/BMIApplet/BMIApplet.html
Shame on Cecil for propagating the misinformation in your esteemed column.
Signed,
-Tall Guy
And yet ironically the very link which you tout here says:
I also find it interesting that this “more reasonable” formula has a citation of “somewhere the author read”.
I should say that it’s intrinsically more reasonable that the power should not be an integer (because it’s an empirical value for a highly complex system), and also reasonable that it should be near 2 (or the correlation would never have been made in the first place).
Cite?
Check the second cite in #21
But insurers have no incentive to deny coverage to healthy individuals. In fact, that’s their prime target. They want to deny coverage to unhealthy people, not healthy people. Healthy people pay premiums but don’t incur costs, which means pure profit for the insurance companies. Unhealthy people who pay premiums but also incur costs are the insurance company’s nightmare.
And people who have undiagnosed serious preexisting conditions make insurance companies wake up in the middle of the night, screaming in anguish, their sheets soaked with sweat.
If, y’know, insurance companies had sheets. Or sweated.
I’m trying to think of any time the insurance industry ever asked me my BMI and I can’t think of any, so I’m gonna need to ask for a cite on that one.
Umm… if we’re going to update the BMI, why don’t we just make it slightly more complex and include a variable that, say, tells us how mass should grow related to height like, say, measuring your waist. It’s always bugged me that I’m classified as “obese” yet, I am in excellent shape and have (or did last time it was measured) single digit body fat percentage. Is it SO much harder to include a waist and/or hip measurement? Wouldn’t that little bit of extra information help one determine if the extra weight was musle or fat?
They don’t need to ask your BMI, just your height and weight. Their computers are quite capable of doing the math.
Now, I can’t remember an insurance company ever asking my height and weight, but then I’ve never bought insurance just for myself. It’s always been through work.
Isn’t there a sense in which weight by itself is a health risk, regardless of body composition? Like, say, a 300 lb bodybuilder may be slightly healthier than a 300 lb couch potato, but both would be a heck of a lot healthier at half that weight? I don’t have the google-skills of capably finding an answer to my question, so I brought it up here.
That’s what I think of anyway whenever I hear “BMI says I’m overweight, but my biceps are 35 inches around and I can bench 250 pounds! It has to be wrong!”
I’m not sure this is what you’re getting at Cube, but any body builder will have to increase their caloric intake to increase muscle mass. Likewise, a marathoner or iron man contestant will need to take in a vastly greater number of calories than they would otherwise.
Decreasing caloric intake has been shown to promote better health:
I don’t know of any research that shows that increasing caloric intake by itself correlates with poor health, but it would seem to follow.
OK, I’m no doctor. But I will say that I’ve never seen anything like that in any article. I’m not sure why you would think that 150 pounds of healthy muscle might be a health issue? :dubious:
Not to mention:
Pharmacy Times
The “Obesity Paradox”
Obesity health benefits
And SiXSwordS’s “low calorie diet = longer health” article has only ever been shown in rats. It’s never been shown in humans.
IANAD nor am I a researcher or a professional in any sense that is germane to the discussion. However, I know it to be untrue that only rats have been tested. In fact, one indication that CR might not help humans is the fact the CR in house flies is detrimental. (cite)
Of course, I think that misses your point. There is always a question as to whether testing rats, mice, cats, dogs etc. gives us valid data about humans, but I believe that at least some researchers believe that CR can be beneficial to humans. (cite)
Fair enough. I just have a compulsion to stridently jump into the conversation whenever it gets mentioned without clarifying that it hadn’t been proven. 
And those CRON people can be scary!