Is BMI an accurate measure or total B.S.?

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  • geekyjock76
    geekyjock76 Posts: 2,720 Member
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    For overweight populations, BMI is not a good indicator.
    For underweight populations, BMI has more merit.
  • SideSteel
    SideSteel Posts: 11,068 Member
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    For overweight populations, BMI is not a good indicator.
    For underweight populations, BMI has more merit.

    Aside from well trained athletes, why do you think BMI is not a good indicator? Additionally, indicator of what?

    I'm typing from my phone so this may come across blunt--not trying to bust your balls. I would like to hear your explanation though.
  • jr1985
    jr1985 Posts: 1,033 Member
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    Go off of Body Fat Percentage... Not BMI,

    A couple of years ago I had a trainer do a body fat percentage thing... Even if I lost every single ounce of fat on my body, which is impossible, I would still be considered in the overweight/obese category according to BMI. Since I have a lot of muscle... I also unfortunately have a layer of fat covering up my pretty muscles :(
  • pyrowill
    pyrowill Posts: 1,163 Member
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    No it's not BS. However it isn't accurate unless you are of the median body composition on which it is based. Which percentage wise, the majority are.

    However, it's not accurate for particularly tall/short/muscly people. BF is better to go by.
  • SideSteel
    SideSteel Posts: 11,068 Member
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    This is just an observation:

    BMI is a general guideline that is going to be reasonable for most people.

    It will likely be off for bodybuilders and possibly other athletes.

    The part I find interesting is that the population that it's less accurate in, is the population that doesn't need to worry about it to begin with.

    I recall thinking it was crap when I first started lifting. The truth is that I was also overweight and overfat and it was accurate for me. I just didn't want to accept it.

    Looking at your photos, I wouldn't say you look on the border of overweight. However, SideSteel has a point- usually the people saying "it's crap! I'm not overweight!" are not bodybuilders and athletes. Those that ARE bodybuilders and serious athletes are correct in that they are heavily muscled and have a great, healthy body fat percentage that BMI doesn't reflect (like a couple of posters on this thread.) However, most of the people I personally have seen on MFP squawking about BMI being nonsense are people who also insist they are "big-boned"...and quite honestly, I do think that it's an excuse a lot of the time.

    This isn't directed at you or even at any one in particular on this thread. It's just a general trend I personally have noticed. But if you're worried, get your body fat % tested and go by that instead.


    In my lean-ish pics I believe I was still considered overweight by BMI standards. However in my original statement I was referring to my starting point 3.5 years ago. I was 5'11 and 200lbs and I believed that I wasn't all that overweight. Having lost 20lbs but also gaining a reasonable amount of muscle in that time (which means my total fat loss was likely higher than 20lbs) it puts perspective on things.
  • NoMoreStretchyPants
    NoMoreStretchyPants Posts: 307
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    I have several friends who body-build and their BMI measurements are going to place them in the over-weight category. So no, I feel that measuring body fat percentage is a better indicator. Body composition is important here. A pound of fat and a pound of muscle is still a pound, but look at how different they are visually.
  • Routerninja
    Routerninja Posts: 201
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    Even at my goal weight because of my frame size I will still be obese by BMI standards. I call total BS.
  • Sarauk2sf
    Sarauk2sf Posts: 28,072 Member
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    It is actually not that inaccurate of an indicator unless you have a high muscle mass - and even then its not that wildly off for women. It can be more inaccurate for men as they can carry proportionately more muscle mass than women.

    If you are a female and well into the overweight category, you probably are overweight to some degree. I doubt you would find (m)any women in the obese category who are not at least overweight.

    However, BF% is a better indicator as t takes into account muscle mass. That being said, most BF% estimation tools are not that accurate.
  • MireyGal76
    MireyGal76 Posts: 7,334 Member
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    It's off base for me. But I guess I am closer to the athlete level and therefore low body fat and higher weight confuse it. Plus I find my 6' height throws it off too...

    I did this for sh!ts and giggles...
    http://www.myfitnesspal.com/blog/MireyGal76/view/body-fat-and-bmi-not-accurate-624726
  • kstand0053
    kstand0053 Posts: 15 Member
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    BMI is a measurement tool that is so cheap and easy; and that is why I don't see it going away any time soon. Measuring body fat % is so much more accurate! I really do wish they would classify more people based up their body fat percentage. But think about this........ how many people would be classified as "obese" if "they" did.......I wonder if the # would go up or down..?
  • SideSteel
    SideSteel Posts: 11,068 Member
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    It's off base for me. But I guess I am closer to the athlete level and therefore low body fat and higher weight confuse it. Plus I find my 6' height throws it off too...

    I did this for sh!ts and giggles...
    http://www.myfitnesspal.com/blog/MireyGal76/view/body-fat-and-bmi-not-accurate-624726


    In your case it would appear that BMI is reasonable in that it classifies you as in a healthy weight range, correct?
  • MireyGal76
    MireyGal76 Posts: 7,334 Member
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    It's off base for me. But I guess I am closer to the athlete level and therefore low body fat and higher weight confuse it. Plus I find my 6' height throws it off too...

    I did this for sh!ts and giggles...
    http://www.myfitnesspal.com/blog/MireyGal76/view/body-fat-and-bmi-not-accurate-624726


    In your case it would appear that BMI is reasonable in that it classifies you as in a healthy weight range, correct?

    I guess, yeah. You are right if I look at the categories. But I think where I got stuck is that it was saying that I was in the middle of average and that it seemed to suggest that I could lose quite a bit more weight and still be healthy. If I look at it solely from a "bucket" perspective and say, "I fall into the I'm healthy bucket", then you're totally right.

    :)
  • myurav
    myurav Posts: 165 Member
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    I have the same issues with BMI - I think it is a good quick guideline for health, but should be taken with a grain of salt. I'm technically an overweight BMI, but my bf% is around 25%, which is in the healthy range. Given that BF% is a better indicator of fitness, I think it's better to use that instead of BMI to monitor progress.

    Also, OP, judging by your pictures, you are nowhere near overweight - damn girl! You look amazing!
  • HanamiDango
    HanamiDango Posts: 456 Member
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    We need some sort of guide for people to go by and no system is perfect. I need to lose a pound according to BMI to be just overweight. Truthfully, I will still be obese until I lose another 10-20lbs. My good weight is at the lower end of the BMI charts.
  • Sarauk2sf
    Sarauk2sf Posts: 28,072 Member
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    In my lean-ish pics I believe I was still considered overweight by BMI standards. However in my original statement I was referring to my starting point 3.5 years ago. I was 5'11 and 200lbs and I believed that I wasn't all that overweight. Having lost 20lbs but also gaining a reasonable amount of muscle in that time (which means my total fat loss was likely higher than 20lbs) it puts perspective on things.

    My anecdote - I am in the group of women who would trend on the higher side of the BMI - significant LBM, wider hips (no comment you!) and a splayed ribcage etc. Even then, I am currently only a fraction into the overweight category. Replace 10lb of muscle with fat (which would put me into a more average LBM for my height), and yep, I would be a bit overweight.

    Also, BMI should be looked at as a continuum/range - which is what it is. You do not lose a pound and suddenly go from healthy to underweight or vice versa.
  • peleroja
    peleroja Posts: 3,979 Member
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    This is just an observation:

    BMI is a general guideline that is going to be reasonable for most people.

    It will likely be off for bodybuilders and possibly other athletes.

    The part I find interesting is that the population that it's less accurate in, is the population that doesn't need to worry about it to begin with.

    I recall thinking it was crap when I first started lifting. The truth is that I was also overweight and overfat and it was accurate for me. I just didn't want to accept it.

    Looking at your photos, I wouldn't say you look on the border of overweight. However, SideSteel has a point- usually the people saying "it's crap! I'm not overweight!" are not bodybuilders and athletes. Those that ARE bodybuilders and serious athletes are correct in that they are heavily muscled and have a great, healthy body fat percentage that BMI doesn't reflect (like a couple of posters on this thread.) However, most of the people I personally have seen on MFP squawking about BMI being nonsense are people who also insist they are "big-boned"...and quite honestly, I do think that it's an excuse a lot of the time.

    This isn't directed at you or even at any one in particular on this thread. It's just a general trend I personally have noticed. But if you're worried, get your body fat % tested and go by that instead.


    In my lean-ish pics I believe I was still considered overweight by BMI standards. However in my original statement I was referring to my starting point 3.5 years ago. I was 5'11 and 200lbs and I believed that I wasn't all that overweight. Having lost 20lbs but also gaining a reasonable amount of muscle in that time (which means my total fat loss was likely higher than 20lbs) it puts perspective on things.

    Oops, I quoted you but was referring to the OP's photos! Sorry for the confusion.
  • littleburgy
    littleburgy Posts: 570 Member
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    It's one indicator on a whole dashboard of information.
  • Pirate_chick
    Pirate_chick Posts: 1,216 Member
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    BMI is not an accurate indicator for people who are bodybuilding or heavy exercisers. You would be better off with a clamp test or "skin fold" or a body fat % test based on the navy/army calculation.

    I mean some of the guys who are in amazing shape would be considered obese under the standard BMI calcuation.

    I think body fat % is far better...esp if your trying to figure out your lean muscle mass.

    All of this. BMI is a joke.
  • wijody
    wijody Posts: 26 Member
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    It is actually not that inaccurate of an indicator unless you have a high muscle mass - and even then its not that wildly off for women. It can be more inaccurate for men as they can carry proportionately more muscle mass than women.

    If you are a female and well into the overweight category, you probably are overweight to some degree. I doubt you would find (m)any women in the obese category who are not at least overweight.

    However, BF% is a better indicator as t takes into account muscle mass. That being said, most BF% estimation tools are not that accurate.

    I agree with this. If you're a body builder or have a lot of muscle, you know it. If that shoe fits, then BMI will be a poor indicator. If you're generally 'soft' and your exercise is more cardio-based, and especially if you're female, I think BMI is a decent indicator.
  • JKardeno
    JKardeno Posts: 24 Member
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    Obviously it isn't accurate if you're a bodybuilder or something. If you're just an average joe who doesn't lift, It's fine IMO.

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