# Is the Body Mass Index a crock? **URL:** \ **Category:** Factual Questions\ **Created:** [October 1, 2003, 11:33pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017 "2003-10-01T23:33:52Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![SnoopyFan](https://avatars.discourse-cdn.com/v4/letter/s/d07c76/32.png) [@SnoopyFan](https://boards.straightdope.com/u/SnoopyFan)\ **Post date:** [October 2, 2003, 1:06pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/21 "2003-10-02T13:06:50Z")
**there’s no way 165 is normal for you.** _Tracks back to see where she wrote “I care about your opinion, Griffin”_ I have no desire to look like a skeleton. I want some meat on my bones even after I’m done losing weight. I want an ass and a slightly rounded tummy and I want to keep my tits. 149 is the most I could weigh and not be condemned by the BMI chart, so I don’t see the harm in an extra 16 pounds, considering at one point my body was carrying 200 extra pounds. So, in short, neener 😛 ---
**Author:** ![The\_Griffin](https://avatars.discourse-cdn.com/v4/letter/t/a87d85/32.png) [@The\_Griffin](https://boards.straightdope.com/u/The_Griffin)\ **Post date:** [October 2, 2003, 1:13pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/22 "2003-10-02T13:13:36Z")
Well on your body be it. You’ll still be overweight though, and putting your health slightly at risk. That’s all I’m saying. Of coarse it’s entirely up to you, but I wouldnt say the BMI is a crock of shit just because you want to be overweight. ---
**Author:** ![The\_Asbestos\_Mango](https://avatars.discourse-cdn.com/v4/letter/t/edb3f5/32.png) [@The\_Asbestos\_Mango](https://boards.straightdope.com/u/The_Asbestos_Mango)\ **Post date:** [October 2, 2003, 1:44pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/23 "2003-10-02T13:44:40Z")
This is turning into an IMHO thread really fast. Now, **AndrewT** > [@](#): > > Umm, girls, breasts have lots of fat, and it counts just as much there as in any other part of the body. Nice try though 🙂 Are you really suggesting that a woman with no little or no spare fat on the rest of her body, but with very large breasts (my mother falls into this category) should try to work off her breast tissue because it puts her body fat percentage over the proverbial hump? Or that the fat in a woman’s breasts, from a health perspective, is equivalent to a beer gut? Also, I really think height/weight ratio is pretty arbitrary. I mean really, should a person with a very slight skeletal frame really weigh the same as someone with a heavy skeletal frame? If a person is muscular, they might weigh 20lbs more than someone with a more slender build but still be fit and healthy. And really, when I get down to my desired weight, the girls probably would constitue a third of my body fat, which means that even with very little fat on the rest of my body, it would still but my body fat percentate into a statistically undesirable range. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [October 2, 2003, 1:58pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/24 "2003-10-02T13:58:06Z")
The BMI is not a crock. It is meant to be used as a very quick calculation that applies to most people. And it does. If someone thinks their ideal weight is 130-136 and BMI suggests 120-136, this is hardly a huge and important difference. The goal of the BMI is not to percent body fat but to provide a rough measure of who should try to lose weight. No clinician thinks this applies to the athletic or stacked. It’s a rough measure. Not perfect. I wouldn’t call it arbitrary. Any “test result” needs to be interpreted and examined in context, and the fact it may not apply to you doesn’t make it useless. That being said, the correlation between waist size and mortality is equally compelling. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [October 2, 2003, 2:27pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/25 "2003-10-02T14:27:31Z")
Actually, IIRC, the common wisdom was that “gut” fat is unhealthier than fat distributed elsewhere on the body. And in any case, there is a perfectly fine evolutionary reason for the breasts to be there, y’know. (In any case, a cursory observation would suggest that either God or Evolution did not come up with this design for the sake of optimizing us to live forever) There is also the fact that each human is different. Nobody “wants to be overweight”, but if we set the target at a point where to a segment of tbhe population it’ll become a tiresome, time-intensive, deprivation-based, painful chore to achieve and maintain (and if you’re lucky enough to achieve and maintain by 3Xweekly sports participation, congratulations; that does not make it the norm for all humanity), and insist that it’s not OK until you get there, what you’ll get is a lot of discouraged people saying “F\*\*k it, I’ll take short-and-happy; pass the cheesecake.” Quite frankly, if I see someone who was 200 lbs over, and now is 20 lbs over, I’ll say, “good job, well done”. Myself, I am 5’9" (1.75m) and used to be 205-210 (95kg) 3 years ago. Am now around 170-175 (78kg), and feelin’ _good_. Could drop a few more? Sure. But I won’t kill myself over taking another year or two to get there. ---
**Author:** ![filmore](https://avatars.discourse-cdn.com/v4/letter/f/7993a0/32.png) [@filmore](https://boards.straightdope.com/u/filmore)\ **Post date:** [October 2, 2003, 2:46pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/26 "2003-10-02T14:46:05Z")
Overweight really means over your ideal weight. Usually this is in terms of what percentage of body fat you have. An ideal percentage of fat for men is about 20% and for women is 25%. If you have more than that, then technically you are overweight since you have more fat than is ideal. It’s too bad there’s not a different term than overweight because that word has such a negative connotation. People think overweight means a fat, sweaty blob that can’t walk up 2 stairs without passing out. But even if you have 5 pounds of fat over your ideal body fat percentage, then technically you are overweight. You might not look fat, but you do have some extra weight. Also remember that ideal weight is **not** average weight. Most people are overweight. One big problem I think we have in today’s society is that we are getting used to seeing that extra weight and we start to think that’s normal. So we see a 5’10 man at 185-190 pounds and he looks normal even though he might be 30 pounds above his ideal weight. That extra 30 pounds is not necessarily a death sentence, but it does cause extra stress on the body that can lead to other problems. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 2, 2003, 3:39pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/27 "2003-10-02T15:39:54Z")
> [@](#): > > \*Originally posted by Thea Logica \* > \*\*I think that would really only work if you took into account breast size. If you’re a D-Cup, your body fat percentage is going to be quite a bit higher than the next chick over with two fried eggs on her chest, all other factors being equal. \*\* Yes, but the fact is, women with huge breasts and relatively low body fat are pretty rare. Remember, we’re not looking for a model that fits everyone perfectly. We’re looking for one that probably fits most people pretty well. BMI is that. ---
**Author:** ![The\_Asbestos\_Mango](https://avatars.discourse-cdn.com/v4/letter/t/edb3f5/32.png) [@The\_Asbestos\_Mango](https://boards.straightdope.com/u/The_Asbestos_Mango)\ **Post date:** [October 2, 2003, 6:48pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/28 "2003-10-02T18:48:19Z")
But again, a model that “fits most people pretty well” is still going to leave a lot of people outside. I would propose a model that instead of just taking in the height/weight ratio, also takes in such things as bone structure, say by measuring the distance between the crests of the pelvic bones and shoulder joints, the afore- and oft- mentioned breast size, musculature (remember, muscle is more dense than fat) and calculates what a person’s desirable weight would be based on that. Waistline relative to the chest/hip measurements should definitely be a factor as well. I mean, really, a 5’2" ample-bosomed woman who is fit and healthy at 140 lbs would be considered overweight according to the BMI… ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 2, 2003, 7:04pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/29 "2003-10-02T19:04:50Z")
Go back and read **Dr\_Paprika** ’s response. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [October 2, 2003, 7:26pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/30 "2003-10-02T19:26:15Z")
I had never heard of BMI until now and I have no idea what is considered normal but I come in at just under 22 and could even (maybe) lose a pound or two but I guess someone my height could have a BMI of 25 and be very muscular. . . or very fat. I think the BMI is a useful first approximation but it only measures very general things like weight and height and adding measurements like percentage of body fat and others would make it a better indicator. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [October 2, 2003, 7:38pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/31 "2003-10-02T19:38:30Z")
> [@](#): > > I would propose a model that instead of just taking in the height/weight ratio, also takes in such things as bone structure, say by measuring the distance between the crests of the pelvic bones and shoulder joints, the afore- and oft- mentioned breast size, musculature (remember, muscle is more dense than fat) and calculates what a person’s desirable weight would be based on that. Waistline relative to the chest/hip measurements should definitely be a factor as well. This would be a better measure. If I was your doctor, it would cost you shoulder and hip X-rays (costing the Ontario taxpayer $250) and might take 10 minutes to calculate. On the other hand, if a patient clearly needs to lose weight, I can calculate a BMI in twenty seconds at no cost. I can compare the BMI of this person to what it was two months ago. It is a useful rough measure – useful since a doctor can calculate it quickly without special tests. The problem is if you interpret the result as “Am I fat or not?”. It is meant to be a rough indicator only, does apply to most people (including some of the whiners here) and is useful not only as the number you get BUT HOW IT CHANGES WITH ADDED DIET AND EXERCISE. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 2, 2003, 7:52pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/32 "2003-10-02T19:52:26Z")
What it all comes down to is that it’s better to get a person to consider their weight as a risk factor for disease when it’s not a problem than to let them ignore their weight when it is a problem. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [October 2, 2003, 7:54pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/33 "2003-10-02T19:54:11Z")
> [@](#): > > \*Originally posted by Thea Logica \* > I mean, really, a 5’2" ample-bosomed woman who is fit and healthy at 140 lbs would be considered overweight according to the BMI… Oh, but just barely. That’s a BMI of 25.6, and the overweight category starts at 25. If you’re going to take it as a precision measurement and misinterpret the categories, you could complain about how somebody with a BMI of 24.9999 could go from “perfectly normal, average and fit” to “overweight and definitely in need of strict exercise” by inhaling too deeply. ---
**Author:** ![Otto](https://avatars.discourse-cdn.com/v4/letter/o/bbe5ce/32.png) [@Otto](https://boards.straightdope.com/u/Otto)\ **Post date:** [October 2, 2003, 8:02pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/34 "2003-10-02T20:02:20Z")
“Based on the size of my waist, I should be a 90-foot redwood.” - Erma Bombeck The BMI calculators (at least the ones I’ve seen online) strike me as a total crock as well. I’m 6’1" and have lost a lot of weight over the last couple years. I can certainly stand to lose some more but according the the BMI calculators I’ve tried I should weigh no more than 168. I don’t find that to be realistic in the slightest. Maybe the ones I’ve tried are wrong and I’m not looking at an accurate scale, but I can say that it’s discouraging as hell to drop over 100 pounds and still be tagged as “obese” on the BMI scale. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [October 2, 2003, 8:23pm UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/35 "2003-10-02T20:23:09Z")
Yes, **Otto** , the ones you’ve been using are wrong. If you’re 73 inches tall, the normal range for your height is 140-190, so you should weigh no more than 190. I think that most online calculators should get this right, so try another one. You won’t be tagged as “obese” until 227 lbs. ---
**Author:** ![Dogface](https://avatars.discourse-cdn.com/v4/letter/d/9d8465/32.png) [@Dogface](https://boards.straightdope.com/u/Dogface)\ **Post date:** [October 3, 2003, 4:15am UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/36 "2003-10-03T04:15:05Z")
I work with a guy whose BMI says he’s borderline morbid obese. He’s about as far from that as can be imagined. His hobby is weightlifting, and he makes sure he gets in the cardiovascular exercise, too. According to the water tank, he has well-below average body fat. But according to the infallable BMI, he is morbidly obese. ---
**Author:** ![Ms2001](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ms2001/32/18463_2.png) [@Ms2001](https://boards.straightdope.com/u/Ms2001)\ **Post date:** [October 3, 2003, 5:45am UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/37 "2003-10-03T05:45:51Z")
I don’t think anyone has said the BMI is infallible. Any decent BMI calculator will tell you it’s inaccurate for bodybuilders. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [October 3, 2003, 7:52am UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/38 "2003-10-03T07:52:17Z")
> [@](#): > > \*Originally posted by Thea Logica \* > \*\*Are you really suggesting that a woman with no little or no spare fat on the rest of her body, but with very large breasts (my mother falls into this category) should try to work off her breast tissue because it puts her body fat percentage over the proverbial hump? \*\* Generally speaking, reducing your body fat by healthy means such as exercise and a moderate diet will reduce fat proportionately over the body. There is no such thing as “spot reduction” short of surgery, for breasts or anywhere else. Every woman of my acquaintance who has lost weight has complained about the reduced size of her breasts. That said, I make no judgement on your mother’s position. There are always exceptions. \*\* > [@](#): > > Or that the fat in a woman’s breasts, from a health perspective, is equivalent to a beer gut?\*\* IANAD, but naively, yes. As I understand it body fat is body fat irrelevant of where it sits. The heart has to push blood through the arteries for every extra kilo of fat, no matter where the fat is. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [October 3, 2003, 9:53am UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/39 "2003-10-03T09:53:32Z")
> [@](#): > > \*Originally posted by The Griffin \* > How tall are you? You could still be overweight with a 28 waist. Yeah, IF I was four and a half feet tall, which I’m not. > [@](#): > > \*Originally posted by The Griffin \* > I think some people fail to realise you can be overweight without being grossly overweight, and you should still try to lose a bit. I think some people are having trouble getting a grip that a significant number of folks don’t fit the BMI straight-jacket. There is one and only one person in my family whose BMI falls under 25 (it’s been consistently around 23 her whole adult life). She has had a half dozen heart attacks, a stroke, and a couple heart surgeries. Meanwhile, the rest of us chug along perfectly fine with our “extra” 20 lbs, some of us chugging well into our 70’s and 80’s. I have no - that’s no, none, nada, zip - blood relatives with diabetes _at all_. Obviously, we do have heart disease in the family. Equally obviously, it’s not tied to obesity. I have no qualms with using BMI as a tool, as long at it’s recognized as a tool with limits. There are a lot of other factors that go into “health”. The whole person needs to be looked at, not just one number. I come from a family where the healthiest - that is, healthy by a _number_ of different measures - all have a BMI of 25-26. That’s partly because, yes, we really _are_ large-framed. That’s partly because we tend to be slightly more active and more muscluar than average for our ages. I’ve had a lot of doctors over the years, and the most any have said about my weight is just be careful you don’t start putting on the pounds at some point. > [@](#): > > _Originally posted by AndrewT_ > > > [@](#): > > > > _Originally posted by Thea Logica_ > > Or that the fat in a woman’s breasts, from a health perspective, is equivalent to a beer gut? > > IANAD, but naively, yes. As I understand it body fat is body fat irrelevant of where it sits. The heart has to push blood through the arteries for every extra kilo of fat, no matter where the fat is. OK, let’s distinguish between _good fat_ and _bad fat_. You really do need _some_ fat in your body (although not in the quantities a lot of Americans are carrying around right now). Fat serves a number of important functions, such as providing insulation under your skin to keep your body heat in, cushioning vital organs such as the heart, and providing storage for energy. The insulation and cushioing fat is NOT the “equivalent of a beer gut” - nor is the fat found as a _normal_ part of a woman’s breasts, and that quantity has a strong genetic component. So yes, you could have a very slender woman with a low overall bodyfat content whose still has tits, perhaps C or D cups, and that is NOT “unhealthy”. A woman with EEE cups might be a different story. In fact, women _need_ a certain amount of body fat to remain healthy. I forget the exact cut-off, but below a certain percentage her reproductive system shuts down. That sort of infertility is seen as a bad thing, usually, even in otherwise fit women such as Olympic athletes. Those women in body-building magazines that look like peeled sides of beef? Terrible. However much they can hoist off the ground, however large their biceps, their bodyfat is _too low_ for good _overall_ health. (Not to mention they’re probably abusing drugs, because that sort of muscle development and definition in a human female is just not natural) ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 3, 2003, 11:49am UTC](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017/40 "2003-10-03T11:49:24Z")
Eh. Getting down to low bodyfat levels doesn’t require drugs for anyone. Building muscles like the female bodybuilders does, but hey, that’s their business. [Previous page](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017.md?page=1) [Next page](https://boards.straightdope.com/t/is-the-body-mass-index-a-crock/205017.md?page=3)