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

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  • jwdieter
    jwdieter Posts: 2,582 Member
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    The problems with BMI tend to come in a few categories:
    1) People who use 22 instead of 25 for BMI normal, or think they should be at 19 for whatever reason. Usually women. It's a very general category. No need to be at the bottom of the range.
    2) People who think athletes like MJ were BMI obese due to they heard it somewhere. He wasn't. He was BMI normal at NC, then beefed up to BMI overweight at his prime. Most lean male athletes are not BMI obese. BMI overweight is standard for lean male athletes in sports that are not running-centric. Running sport athletes are mostly BMI normal.
    3) Overweight people who are a bit delusional and/or just don't like the classification. Get lean and then figure out what BMI says. Most lean people will end up in normal, because that's just the way it works.
    4) Muscular or abnormally tall people who run into insurance problems due to rigid policies. That sucks.

    I'm lean and BMI overweight. I understand why - and if I didn't, every BMI calculator explains why. It's not a problem with the system.
  • Sarauk2sf
    Sarauk2sf Posts: 28,072 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.

    I would argue that outliers like bodybuilders does not make the BMI a joke - just not a good indicator for a small percentage of the population
  • Elsie_Brownraisin
    Elsie_Brownraisin Posts: 786 Member
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    24ply0l.png

    They should go ahead and change it in the same way to make us all average...

    When I had a BMI of 39, I wasn't no elite athelite, but perhaps you'll have more people on MFP that have skewed numbers because of exercise, rather than pies.
  • fast_eddie_72
    fast_eddie_72 Posts: 719 Member
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    It's a tool, and honestly, it does what it's supposed to do very well. It isn't intended to fit everyone in every situation. It's intended to be very easy to check and give an indicator.

    My personal anecdote is kind of the opposite of yours. A year ago I was knocking on the door of "obese". Recently I moved into "normal". The mirror says there's still a bit of fat to lose, so it's becoming kinda clear that I'm a bit puny under the fat. It's a tool, just like the scale. A lot of people say the scale is useless too, but honestly, it's the ideal indicator of change. The scale, over time, tells you without a doubt if your diet is generating a calorie surplus or deficit. BMI charts are similar. They give you a scale to measure against.

    But you have to use it in context. It would be silly for me to say "Hey, I'm done!" just because I moved into a new area of a chart, when the mirror is telling another story. Same for you - looking at your pics, it would be silly to worry about where you fall on that chart without considering any other factors. Where mirror + BMI is telling me I'm out of shape, it's telling you the opposite.
  • 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.

    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.
    I just believe a fair amount of the active population gets grouped into the obese category while scoring favorable marks in other tests assessing quality of life and risks of disease. In my time on MFP and as a personal trainer, I've witnessed a lot of people who fall in this category, yet are otherwise healthy, stress over it to the point of adopting rather unhealthy attitudes and behaviors. At the very least, the ranges should be updated to reflect populations with slightly higher lean mass due to activity.

    To clarify: I feel it has more merit for those of underweight (in terms of health markers) compared to persons slightly overweight.
  • nxd10
    nxd10 Posts: 4,570 Member
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    BMI was designed to compare GROUPS not individuals. It works okay for that.

    BMI works pretty well for average people as an indicator of where you fall relative to other people if you are average - in other words, if you don't have a lot more muscle than average.

    People who are obviously thin shouldn't look at BMI. People who obviously have no fat shouldn't look at BMI. People who think they look 'pretty good' and find their BMI is a lot higher than they think it is might want to think about whether they are fatter than they think they are.

    Statistical measures are as good as the people who interpret them.
  • missdibs1
    missdibs1 Posts: 1,092 Member
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    BMI isn't totally BS. it is/was used by insurance companies to help determine risk of illness and death. It has the benefit of being quick and easy (and cheap) to determine, unlike BF %. Disadvantage is that it doesn't take into account BF% so doesn't apply to very fit people. Overall, I think it's a good starting point.

    So it is a methodolgy to over charge fit and healthy people? You just said the insurance companies use a method they know gives skewed results.
  • dayone987
    dayone987 Posts: 645 Member
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    BMI isn't totally BS. it is/was used by insurance companies to help determine risk of illness and death. It has the benefit of being quick and easy (and cheap) to determine, unlike BF %. Disadvantage is that it doesn't take into account BF% so doesn't apply to very fit people. Overall, I think it's a good starting point.

    So it is a methodolgy to over charge fit and healthy people? You just said the insurance companies use a method they know gives skewed results.

    I didn't say that insurance companies should only use BMI but it is a starting point. Overall, it does give a pretty good probability in regards to illness and death, which is how they make their living. They also look at other factors such as smoking history, previous illnesses, family history etc. I would agree that they should include BF% in their assessment.

    As other posters have pointed out, most people who are are overweight or obese on that scale probably are in reality overweight/obese.
  • fast_eddie_72
    fast_eddie_72 Posts: 719 Member
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    Insurance companies can do whatever they want. They do that kind of thing all the time. My son is the safest driver I know, but you think he gets a break on car insurance? He's an 18 year old boy with a twin turbo, 300+ HP car. Statistics say he's a risk. That's how it works. It's not fair, but that's how it works.
  • peleroja
    peleroja Posts: 3,979 Member
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    BMI isn't totally BS. it is/was used by insurance companies to help determine risk of illness and death. It has the benefit of being quick and easy (and cheap) to determine, unlike BF %. Disadvantage is that it doesn't take into account BF% so doesn't apply to very fit people. Overall, I think it's a good starting point.

    So it is a methodolgy to over charge fit and healthy people? You just said the insurance companies use a method they know gives skewed results.

    The percentage of people who have healthy or athletic body fat amounts who show up as overweight and obese on the BMI chart is likely astonishingly small compared to those who actually ARE overweight or obese. Really muscular people with low body fat are the exception, not the rule.
  • lesteidel
    lesteidel Posts: 229 Member
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    It's b.s.

    It's good as an average for all people. But not all people are average.


    The pinch an inch test is way more accurate of whether you need to lose weight.

    If you can pinch more than an inch of fat, you have fat to lose. If you can't. Yay you!!
  • cathylopez1975
    cathylopez1975 Posts: 191 Member
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    I noticed last time I was in to see my cardiologist he was now including BMI. I had congenital valve surgery 2-1/2 years ago at a weight of 237 lbs. I weighed 146 when I saw the cardiologist this year. Obese to normal BMI. Dr.'s only comment - taking the weight off really helps cardiac function. No comment on BMI. I also had an echocardiogram, he looked at my feet/ankles, listened to my chest, and asked about symptoms such as shortness of breath and water retention.

    I assume a cardiologist/doctor uses BMI as part of the picture like mine did. Especially when they see people who would be dealing with cardiac issues.
  • 24lol25
    24lol25 Posts: 49
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    The method of only using hight and weight isn't that accurate. That method has no regard to muscle weight.
  • ninerbuff
    ninerbuff Posts: 48,708 Member
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    BMI is fine....................................if you don't have or want any lean muscle weight.

    A.C.E. Certified Personal/Group FitnessTrainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 30 years and have studied kinesiology and nutrition
  • TheEffort
    TheEffort Posts: 1,028 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.

    Agreed.
  • NRBreit
    NRBreit Posts: 319 Member
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    The percentage of people who have healthy or athletic body fat amounts who show up as overweight and obese on the BMI chart is likely astonishingly small compared to those who actually ARE overweight or obese. Really muscular people with low body fat are the exception, not the rule.

    I would agree with this. Another important factor is frame size. If you're a small/medium frame with a 24+ BMI, you're probably overweight (even if you lift/exercise and have good muscle mass). Now, if you have a large frame, being at the top end of normal BMI or slightly over is probably pretty normal.
  • salvyhead
    salvyhead Posts: 66 Member
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    BMI was designed to assess the weight of populations, not individuals. So I generally take it with a grain of salt.

    Here's an thought-provoking opinion piece on it which helped guide my thinking away from obsessing over it.

    http://www.npr.org/templates/story/story.php?storyId=106268439
  • albionjen
    albionjen Posts: 86 Member
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    I think BMI is a reasonable guide for people who are just starting on the road to fitness. It is mostly useless if you are within "healthy BMI" or only just overweight and do a reasonable amount of exercise.

    The BMI formula ended up being a reasonable guideline for me:

    If you do little exercise and have BMI of 35 then yes you really are obese and need to lose a load of weight to be healthy. That was me about 15 months ago :laugh: It was helpful for me to know what kind of weight I should be aiming for and to be honest it was helpful to realise that I needed to lose at least 25kg in order to be a healthy weight.

    Now that I lost about 27kg I am in the upper region of "healthy BMI" and I am more or less happy with how I look. I've switched to ignoring "weight loss" targets now and focusing more on (a) how I look in the mirror (b) how clothes fit (c) athletic performance. I expect to bump up my calories very soon so I don't lose any more weight, and the decision to start maintenance mode will NOT be based on what I see on the scale or some idea of "ideal BMI". My ticker only shows a target as you have to set one in order to use the site!
  • akillilea0812
    akillilea0812 Posts: 115
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    The percentage of people who have healthy or athletic body fat amounts who show up as overweight and obese on the BMI chart is likely astonishingly small compared to those who actually ARE overweight or obese. Really muscular people with low body fat are the exception, not the rule.

    I would agree with this. Another important factor is frame size. If you're a small/medium frame with a 24+ BMI, you're probably overweight (even if you lift/exercise and have good muscle mass). Now, if you have a large frame, being at the top end of normal BMI or slightly over is probably pretty normal.

    Good points guys! It is just a guide and of course there are going to be exceptions. If you want an accurate measurement a skin fold test is good. If you have access to it you can also try the bodpod or a hydrostatic body fat test (check with your local university, alot of the exercise science labs have one or both of these options). We were lucky enough to have all of them when I was in school and it is really cool to be able to compare your results from the different tests.

    Well... I thought it was cool at least :glasses:
  • Victoria2448
    Victoria2448 Posts: 559 Member
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    Total BS!

    I am in the overweight range of BMI...Hmmmm?:laugh:

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