Ignoring BMI

jwdieter

BMI is easy. It has huge ranges. It has a lot of caveats.

BF can be off by a ton (20%+), with the various ways people measure it.

I dropped from 27.8 to 23.7 recently. At the top end, I could do 20 pull ups and had perfectly healthy blood work and blood pressure. Now I can do a lot more, and have more visible side ab striations.

Anyhoo, when I see people who aren't jacked, have a gut, and are unhappy with BMI labels, it just seems kinda rationalization-y. It's not a perfect measurement system by any means, but most people simply aren't abnormally muscled.

WendyTerry420

I ignore BMI. My goal weight is "overweight" by BMI, but I agree that BF% is a better indicator than scale weight.

UsedToBeHusky

BMI doesn't calculate for body composition at all. Nor does it account for variations in your body's frame.

But then again, body fat cannot be accurately calculated without getting dunked.

I say just do what feels good, looks good, and seems right.

ItsCasey

From the CDC's website:

If an athlete or other person with a lot of muscle has a BMI over 25, is that person still considered to be overweight?

According to the BMI weight status categories, anyone with a BMI over 25 would be classified as overweight and anyone with a BMI over 30 would be classified as obese.

It is important to remember, however, that BMI is not a direct measure of body fatness and that BMI is calculated from an individual's weight which includes both muscle and fat. As a result, some individuals may have a high BMI but not have a high percentage of body fat. For example, highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness. Although some people with a BMI in the overweight range (from 25.0 to 29.9) may not have excess body fatness, most people with a BMI in the obese range (equal to or greater than 30) will have increased levels of body fatness.

It is also important to remember that weight is only one factor related to risk for disease. If you have questions or concerns about the appropriateness of your weight, you should discuss them with your healthcare provider.

They are using "highly trained athletes" as an example, probably because it's easier for the average person to picture a football player as a muscular person who weighs a lot but doesn't carry excess body fat. But the same principle applies to people in the general population, not just to athletes.

So a BMI in the "overweight" category does not necessarily mean you are carrying too much body fat. But if you're in the obese category, you probably are, regardless of how much lean mass you have.

jwdieter

Few examples of Olympic medalist sprinters (all accused of doping), who are in "normal" BMI range:

TheCaren

I think BMI is a blunt tool, and it's more suited for measuring populations rather than individuals.

^^^^ This is a great description. I think it makes a nice, broad generalization. A guideline to use if you're not doing anything more extensive to get a handle on where you are at weight-wise. But not all body compositions are the same. So one must take this number with a grain of salt...

shadus

BMI is a rough tool. It's meant to give a valid range for 95% of the population. If you're one of those who are naturally either bigger or smaller than the remaining 95%... it may not work right for you. It's a guideline, that is repeated all over the place when you read about BMI. That said... eyeballing bf% is subject to a large number of personal biases and I'd not trust my own eyeballing of myself half the distance I could throw me wind in a hurricane. Eyeballing is known to be the absolutely least accurate method subject to +/-10% (for someone trained to do it.) You're basically just guessing without any real evidence backing it up. You're better off with a weight loss scale which can be 5-8% off commonly or calipers (if you can use them accurately and with consistency... which most can't without training.)

I'm a 5'9" male and my BMI "healthy" range is between 125lbs and 168.5lbs. At 125lbs I'd look anorexic at best... but the honest truth is, unless you have your body fat measured accurately (dexa scan) when you believe you are at an appropriate weight to verify the bf%, there is no good way to know if bmi is accurate for you or not. If in doubt, assume it is.

micheleld73

How is it that BMI is ignored/dismissed only by overweight people?
If an underweight would happen to say something like this you would all send him/her to the doctor regardless of bone structure or eating habbits.

According to fat to fit ratio I need to lose a few more lbs. to be at my ideal weight versus BF%. But if I look at my BMI it says I'm underweight...so not only overweight people disregard BMI!!!

SteelySunshine

BMI is probably the worst measurement to assess how healthy a person is. It's basically a fancy height weight chart so not only is it a bad tool it's a redundant one as well.

I am 5'4" and have lean mass of 175 pounds. I am certain to lose some of that. But, I seriously doubt I will lose 75 pounds of it. Which is what I would have to lose to have a shot at getting into a normal BMI range. So far my estimate is that I will lose 20 pounds or so based on how much LW/BF that I have lost so far. No matter how I crunch the numbers I will still be over weight even if I get down to 15% BF.

Now my youngest daughter has about 140 pounds of LW and she was advised to get down to 18% BF. I don't think she will lose very much LW a couple to 5 pounds at the most. She will still be considered overweight by the BMI charts, but not obese. I will still be obese.

BTW my theory is that larger framed people with a lot of LW need to have a lower BF% than average framed people. So, I am not going to stop at at the 25% bf that I was advised to do.

QueenBishOTUniverse

Ok, here's my basis for estimating. Based on the pictures in this link I would put me at 35%

http://www.builtlean.com/2012/09/24/body-fat-percentage-men-women/

Based on the pictures in this link I would put me at 30%, but my husband says my waist is more defined than what is in the picture.

http://www.leighpeele.com/body-fat-pictures-and-percentages

YMCA calculates me at 31%, the navy calculates me at 40% and my weight loss scale says I'm at 35%

Averaging them all together, I'm pretty comforatable just going with 35% and not paying money to get dunked in a tank.

PS no idea how to just post the pictures so if someone wants to clue me in that would be awesome...:happy:

chesao

I know that this thread is ten days old, but rather than starting a new one specifically for my needs, I just want to throw my issue with BMI into here. Roughly 6% of my weight can be accounted for by my breasts. On top of that, I don't really tend to lose much breast weight, as I simply have a lot of breast tissue (I mean, there's obviously fat there, but my breasts are quite dense). If I calculate my BMI without including my breast weight (which I calculate through water displacement, for those curious), it drops almost two points. I don't necessarily hate BMI or think that it's a crock, I just think that it's not only athletes, who are more than two standard deviations away from the norm. Whether I'm correct in that assumption, I don't know, but obsessing over BMI just doesn't work for me.

PS - boobies. :flowerforyou:

stefjc

And when you have all finished with BMI... what about skinfold calipers?

I was told something by a Professor and have never been able to ascertain just how much of his story was true and how much was to make a point about such measures.

Does anyone have any proper info on how they came about? Info that does not originate with the manufacturers?

FitForeverAgain

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I'm "BMI Overweight" and apparently need to lose 8 pounds to get to normal. Take nothing as an absolute in fitness. When in doubt, workout more and eat cleaner.