So how much BS is BMI?

"Chairman Kaga" (mike-mckinnon)
07/23/2014 at 13:08 • Filed to: None

My wife and I have been dieting a bit, trying to cut out sugar and excessive carbs. I started at 205 (I'm 5'11") in January and am now right at 186. That's good, right?

Well, my employer hosts an annual "health fair" where they offer biometric screening. My cholesterol is good, my glucose is fine, even my BP is normal. But they hammered me on my BMI. According to the nutritionist, I need to weigh 150-160 to qualify for their "healthy incentives" program. Basically it's free HSA money for people who meet a certain set of metrics, which is on the low to middle end of the "healthy range." I know they aren't using this data to jack up my premiums or anything (thanks, Obama), at least.

ANYWAY, for me to get to that weight I'd be at less than 10% body fat, but also have to drop about 15-20 pounds of muscle. Ummm. I asked my doctor and he said yeah, technically I need to be rail thin, even though I have a typically northern European build (tall and broad, "thick" in hip hop parlance).

Ugh. I plan to try and get down to 175-180, which I feel is a healthy weight for me and a little less than I weighed when I was in legitimately good, moderately athletic shape. I can't exercise much at the moment due to a bad rotator cuff and a matching pair of herniated discs with a pinched sciatic nerve. Getting old sucks. Still...

DISCUSSION (38)

RamblinRover Luxury-Yacht > Chairman Kaga
07/23/2014 at 13:10

150-160? Total horseshit.

505Turbeaux > Chairman Kaga
07/23/2014 at 13:14

I dont think 150-160 is a good weight. I am 6' even, and I was pushing 215 for a bit. I am back at 180, 170 would be me being too thin. Hell I used to wrestle at 145 when I was 5'10 in high school and I used to have to starve myself to make weight.

Laird Andrew Neby Bradleigh > Chairman Kaga
07/23/2014 at 13:14

BMI = BS, simple as that. I'm 172cm tall (5,7 or 5,6 right) and 88Kg (195 LB or something), that puts me VERY close to Obese, sure I've got a few pounds more than I should, but I ain't HUGE either. I've got a tad more bodyfat than I should though.

For Sweden > Chairman Kaga
07/23/2014 at 13:14

Just strive to get below 10% body fat, and whatever you weigh is fine.

PelicanHazard > Chairman Kaga
07/23/2014 at 13:16

Quite BS. Best use I've heard for it is monitoring populations ( not individuals) for obesity/famine.

Leadbull > Chairman Kaga
07/23/2014 at 13:16

BMI doesn't take into account the fact that people are built differently, even at the same height. Different bone structures, different muscle masses, etc. It's quite BS.

RamblinRover Luxury-Yacht > Chairman Kaga
07/23/2014 at 13:19

Here, let me borrow from the Wikipedia to explain why:

For a given height, BMI is proportional to mass. However, for a given mass, BMI is inversely proportional to the square of the height. So, if all body dimensions double, and mass scales naturally with the cube of the height, then BMI doubles instead of remaining the same. This results in taller people having a reported BMI that is uncharacteristically high compared to their actual body fat levels. In comparison, the Ponderal index is based on this natural scaling of mass with the third power of the height. However, many taller people are not just "scaled up" short people, but tend to have narrower frames in proportion to their height. Nick Korevaar (a mathematics lecturer from the University of Utah) suggests that instead of squaring the body height (an exponent of 2, as the BMI does) or cubing the body height (an exponent of 3, as the Ponderal index does), it would be more appropriate to use an exponent of between 2.3 and 2.7 [6] (as originally noted by Quetelet). (For a theoretical basis for such values see MacKay. [7] )

Tl;dr: people who are proportionally larger than average instead of just being thin absolutely get fucked by BMI. People who are a good bit shorter than average, and thus have very short proportions compared to their trunk size also get fucked by it.

Borrowing again:

...many people, including physicians, have come to rely on its apparent numerical authority for medical diagnosis, but that was never the BMI's purpose; it is meant to be used as a simple means of classifying sedentary (physically inactive) individuals, or rather, populations, with an average body composition.

In short, since Fed health guidelines pressure the adoption of health standards by providers and insurers, and this usually takes the form of the BMI, this is your government atwerk.

trmoore09 > RamblinRover Luxury-Yacht
07/23/2014 at 13:23

Yea, I'm 6'4 and supposed to be under 205 to even be in the "Normal" range (152-205). Not gonna happen. Currently at 239, and not really "fat" by any means. I've recently lost ~11 lbs and gone from "Obese" to the upper end of "Overweight". BS

Sn210 > Chairman Kaga
07/23/2014 at 13:24

my optimal bmi would put me at 122lbs. Fuck that.

OPPOsaurus WRX > Chairman Kaga
07/23/2014 at 13:24

I'm with you. I'm right near you in height and weight. I couldn't imagine weighing 160.

RamblinRover Luxury-Yacht > trmoore09
07/23/2014 at 13:27

I have a younger brother that looks about 3 months into a gulag stay at 6'5, and he's solidly centered in "overweight". If he were "normal weight" he'd be fucking DEAD. Broad shoulders, long arms, a pinch of muscle = BMI absolutely shitting itself.

tromoly > Chairman Kaga
07/23/2014 at 13:28

My 6' 1" brother, who routinely goes on 100+ mile bike rides and does not have any handles of any kind anywhere on his body, was told a couple years ago at a routine check-up that he needs to lose weight. He weighs 175 pounds and wears size 30 jeans, BMI is a load of crap.

Saracen > Chairman Kaga
07/23/2014 at 13:29

BMI is %100 bullshit.

My brother is a 6'3", 210 pound triathlete. His BMI is 26.2, or at the bottom end of overweight.

I'm 6'4" 250 pounds. I'm not in great shape, but decent shape. I'm into boxing, rock climbing, hiking, cycling, and WMA. I have healthy eating habits. According to my BMI of 30.2, I'm obese.

We're both big-bodied guys...we both played offensive line in HS football. But because we don't conform to some one-size-fits-all metric, BMI would have us think we are very unhealthy.

BMI is ridiculous, and misleading. I think it should be banned. It should never be used, by anybody, ever.

TJDMAX > Chairman Kaga
07/23/2014 at 13:29

BMI is a pretty hard thing to measure. I'm 5'11", 185# with a BMI of 11% (according to a few methods). I work out regularly (6-7 times a week) and a mix of cardio and weight lifting. I consider myself in decent shape with an athletic build. As i'm sure you're aware a pound of muscle and a pound of fat are going to be two different sizes,. Is your company saying in order to qualify you need a certain weight or a certain BMI? If its a certain weight thats dumb, if its a certain BMI it would make much more sense and be much more logical. It is possible to have two people, both 5'11" weighing 200lbs with different BMI's. Muscle weighs more than fat and a "fatter" person obviously has the higher BMI. Not sure which method they are using to measure BMI but there isn't one method that is tremendously accurate. The handheld devices are the least accurate, the dunk tanks are better, and the calipers are slightly better.

Moral of my post, is that your company is retarded if they are requiring a certain weight for each height for this program, it should be based off BMI.

GhostZ > Chairman Kaga
07/23/2014 at 13:29

BMI is good for one thing, and one thing only: Heart health. That's because both weight AND height significantly effect the strain on your heart. It has nothing to do with nutrition, body chemistry, muscular health, etc. It was mostly adopted to give doctors a clear standard for recommending weight loss or weight gain because the US is in a major heart disease scare right now.

That's why some bodybuilders will have overweight BMIs. They should only be concerned if that added weight (in muscle, mind you) strains the heart.

A low BMI would be a problem if there was inadequate fat for the body to store with, otherwise you get into nutritional deficiencies and the body has to break down muscle to survive.

Likewise, someone like me who is persistently underweight (BMI around 17, eat ~3600 calories a day, medical anomaly) is still healthy because I maintain a good body fat ratio and a very nutritious diet. The only way for me to gain weight is to work out, since I can't eat enough to gain any fat, but muscle weight stays.

If you really want to know heart health though, you need to know cholesterol levels (which aren't always indicative of problems either) and blood pressure (which changes quickly). It's a very dangerous and tricky place to be in, trying to understand your own heart. Rather than relying on a doctor once every 6 months, you should get your own heart monitor (and maybe a blood sugar or cholesterol monitor) and check your own blood pressure at various times of the day and keep a record to know where you stand.

So that means that while BMI can be a good indicator of heart strain, it's stupid to use as an indicator of 'overall health'. There are way too many other factors.

mcseanerson > Chairman Kaga
07/23/2014 at 13:30

I know that feeling. I'm 6'0" and wear a 58 coat size. I could be in the 40s and still button it but I'd never get my shoulders in. Lowest weight I have ever been is 225 lbs and if I got below 200 lbs I would just look weird.

trmoore09 > RamblinRover Luxury-Yacht
07/23/2014 at 13:32

Yep, I'm the same way. I'd be anorexic/dead if I were in the "normal" range. I weighed 185 and high school and looked too thin. I couldn't imagine 15X's being "Normal" for me.

CAR_IS_MI > Chairman Kaga
07/23/2014 at 13:43

I prefer BMI over actual body weight. Not everyone has the same frame and / or muscular build. You and I could be the same height but at 10% BMI I could be 150 lbs while at 10% BMI you could be 180 lbs just becasue of body types.

Hell if I told you I was 6'5 265 lbs you would probably say I was a bit on the heavy side. But if I then told you my name was Dwayne Johnson you would realize I was instead just extremely muscular.

Depending on your age 10 - 15 % BMI is generally considered healthy for men.

ColoradoTaco > Chairman Kaga
07/23/2014 at 13:51

I have a similar build to you, I haven't been 150 since 7th grade. Even at 185 I'd be skeletal.

yamahog > TJDMAX
07/23/2014 at 13:52

I think you're getting body fat percentage confused with BMI (bascially height vs weight).

treesmakewater > Chairman Kaga
07/23/2014 at 13:52

i have to call BS I'm 6'7" and when I weighed 230 I still looked like a rail. Now I'm 215 (its mountainbiking weather, yo!)

RamblinRover Luxury-Yacht > TJDMAX
07/23/2014 at 13:52

BMI is a calculation purporting to indicate body fat percentage, body fat percentage (BFP) as actually measured re: adiposity is something wholly different and not to be confused with it.

The "BMI" calculation is *identical* for two people who are 5'11" and 200lb, hence the problem.

Mattbob > Chairman Kaga
07/23/2014 at 13:53

Yeah, you should make them get out the fat calipers. BMI is shit. I am dead center to a little heavy in the healthy BMI range and I'm 6'2" 175lbs. In my opinion that's pretty thin, not middle of the road.

TJDMAX > RamblinRover Luxury-Yacht
07/23/2014 at 13:54

I thought BMI was body mass index which basically said what your fat precentage was. My apologies for being mixed up. Then in your case it is dumb having a BMI requirement.

treesmakewater > trmoore09
07/23/2014 at 13:54

dont forget about muscle mass. When it gets worm out I lose 15-35 pounds from biking, but I begin to gain weight again due to muscle.

TwinCharged - Is Now UK Opponaut > Chairman Kaga
07/23/2014 at 13:55

A lot of BS. I think it's rather like that old rule "i before e except after c" - there are so many exceptions that the rule really doesn't apply. Body mass is dependent on so many factors that IMO you simply can't place then all under one single classification i.e mass. BMI also isn't a great indicator for health - I might be classified as normal but I know I'm a lazy slug that hasn't exercised and has watched the kilos slowly pile on as I flop about uselessly - I know I've gained weight but it still doesn't tell me if I'm healthy or not.

Also, someone might have a higher BMI than myself and be classified as overweight, but that mass might be additional muscle mass compared to mine. Despite being classified as overweight on the BMI, they'd end up better off at the end of a 20 minute stint in a 300cc go kart, because their arms wouldn't be shaking like mine did, as they have more muscle.

jariten1781 > Chairman Kaga
07/23/2014 at 13:58

I did an experiment to see what it's like at the bottom of the BMI 'normal' category. I'm dead nuts 6 ft so that meant getting down to 140. Needless to say that sucked.

davesaddiction @ opposite-lock.com > Chairman Kaga
07/23/2014 at 13:59

Completely bogus. Any metric that would classify pro athletes as obese is worthless for evaluating individual health.

RamblinRover Luxury-Yacht > CAR_IS_MI
07/23/2014 at 14:07

That's fat percentage, not BMI. BMI purports to provide a number calculation based on height and weight, not fat measurement per se. Since this number flagrantly ignores the square/cube law and actual tendencies of body shape, it is often less than useless for people.

Those two hypotheticals you cite? Yeah, they have different *BMI*, but not fat percentage, and the 180lb guy will be considered fat. Function of height squared relative to weight only, fuck all to do with body type - that's BMI.

crowmolly > TJDMAX
07/23/2014 at 14:08

No, it isn't.

ttyymmnn > Chairman Kaga
07/23/2014 at 14:09

BMI is a meaningless, and maybe dangerous, metric. However, it gives the bean counters something to count.

http://www.npr.org/templates/stor…

Victorious Secret > Chairman Kaga
07/23/2014 at 14:10

Medically, BMI is bullshit.

We still use it a lot. Its a way to gauge sedentary behaviour, but it tries to compare against a population which absoultey fucks people who don't conform to the standard.

Carl (@stuffcarlsays) > Chairman Kaga
07/23/2014 at 14:10

Nurse, cancel my 1-o-clock.

crowmolly > Chairman Kaga
07/23/2014 at 14:16

6' 3" 240lb weightlifter here.

According to BMI I am obese, however last time I was at the doctor (who is a PCP with a specialization in sports medicine and orthopedics) I asked him to do a body fat test for insurance purposes. That combined with a decent resting heart rate makes Blue Cross happy. If you really think BMI is out of line for you see if they will do a body composition test.

BMI in itself is not *total* crap as it is "good enough" for most people out there. You hear about a lot of special cases but keep in mind the average US male is 5' 9" and around 200 lbs. Most people think their body fat percentage is way lower than it actually is. I've had a lot of people at the gym boast about their single digits when they probably weren't even out of the teens. There's also a lot of BF testers out there that are dependent on hydration so the results can be skewed pretty heavily.

ttyymmnn > Chairman Kaga
07/23/2014 at 14:17

186 is fantastic. Don't let those bean counters tell you any different. I'm 5'11", and I wish I could be 186.

You can tell a Finn but you can't tell him much > TJDMAX
07/23/2014 at 14:19

Here is a BMI calculator. You put in your weight and height and it calculates BMI. Body fat percentage on the other hand needs to be measured through a pinch test or other method.

http://www.bmi-calculator.net/

lonestranger > Chairman Kaga
07/23/2014 at 14:20

I know that ttyymmnn has already said it, but I feel it's worth repeating in case anyone misses it:

1. The person who dreamed up the BMI said explicitly that it could not and should not be used to indicate the level of fatness in an individual.

The BMI was introduced in the early 19th century by a Belgian named Lambert Adolphe Jacques Quetelet. He was a mathematician, not a physician. He produced the formula to give a quick and easy way to measure the degree of obesity of the general population to assist the government in allocating resources. In other words, it is a 200-year-old hack.

http://www.npr.org/templates/stor…

Renescent > Chairman Kaga
07/23/2014 at 19:59

Under 6', under 200 lbs. Good rule my Army doc buddy said to live by.