BMI and muscle mass

JasperTheStudent
JasperTheStudent Posts: 20
in Health and Weight Loss
Hi, I am a 26 year old student who's been losing weight for more than a year. Today i entered the healthy BMI zone after losing 18 kg (my BMI is 24.9 now). The thing is, I think this BMI is very inaccurate for me, because I am naturally muscular (I am lucky with my genes). When my bmi was 25.5 I could run 8 km in 33 minutes (15 km/h) - not something an overweight person should be able to do.

What do you think? And how accurate is bmi for you?

Replies

  • 3laine75
    3laine75 Posts: 3,069 Member
    BMI doesn't take lean mass into account, it's quite outdated and wasn't designed for what they use it for. Fat % would be a better way to measure health but it probably won't change anytime soon.
  • kelly_e_montana
    kelly_e_montana Posts: 1,999 Member
    My body fat is in the healthy range, as is my hip to waist ratio, and my waist to height ratio. My BMI, however, says I am definitely obese and need to lose 25-50 pounds. If i were in the mid range of my BMI, I would have 1 pound of non-lean mass and would be dead.
  • JasperTheStudent
    JasperTheStudent Posts: 20
    Interesting kelly! I am glad you are not in the healthy range then ;)

    Elaine, you're right. It's a bit strange that it's still in use. Why not use a better formula? Anyways I will forget about bmi myself, it does not work for me. If I would do some serious strength training, I could become very overweight according to bmi in a year or so ;)
  • Dewymorning
    Dewymorning Posts: 762 Member
    BMI is very accurate at calculating your body mass.

    It doesn't calculate what percentage of your body mass is muscle or fat or other lean body mass.

    Also, while BMI is a good measure of the health of a demographic group, it is not the best indication of health in an individual.

    In fact, studies have found that weight as a lone measure is only statistically significant at the extremes (underweight and (morbidly?) obese), and the once other health factors are taken into account (diet, smoking, alcohol, exercise) there is no statistically different life expectancy between someone in the normal weight category and overweight category.
  • cafeaulait7
    cafeaulait7 Posts: 2,459 Member
    As far as how I look, I do look best when I get into 'normal' for BMI. But my lean mass is higher than the low end of my 'normal' range for height. I'd definitely not want to weigh the same as my lean mass, lol. For my frame, that number is silly thin and wouldn't be as healthy as more weight due to LBM.

    When I'm in the high end of normal, some people might think I'd look pudgy, since it's so close to 'overweight'. Nope. I just have a wide skeleton and a good amount of muscle (always did). But to look bulge-less (not so important for health, mind you), I really do like to be in the normal range, yeah. If I added a bunch of muscle, I could see being 'overweight', trim and buff all at the same time!

    I never felt particularly unhealthy just into the overweight range. My diet itself and lack of exercise was more important to change than those few pounds, imho. For someone with a small build, though, it wouldn't be just a few pounds. Folks don't always realize that, yeah.
  • unFATuated
    unFATuated Posts: 204 Member
    The reason BMI is still used (by medical professionals, insurance companies, etc) is because it's easy - you take two easy to get numbers and plug them into a calculator. Done. Finished. All sorts of assumptions are made based on this figure and for a good number of people they're incorrect. A better measure would be a Dexa scan which shows how much lean mass to body fat you have, but then you have to schedule appointments for people, get people to analyse results etc etc. It's very inconvenient when you just want a quick measure of how 'healthy' a person is.

    However, an individual can be within the 'normal' BMI range, but still have a lot of visceral fat and be basically unhealthy and another individual can be in an 'overweight' or even 'obese' range but be quite slim and healthy with a good amount of lean mass and low body fat %.
  • Azdak
    Azdak Posts: 8,281 Member
    Hi, I am a 26 year old student who's been losing weight for more than a year. Today i entered the healthy BMI zone after losing 18 kg (my BMI is 24.9 now). The thing is, I think this BMI is very inaccurate for me, because I am naturally muscular (I am lucky with my genes). When my bmi was 25.5 I could run 8 km in 33 minutes (15 km/h) - not something an overweight person should be able to do.

    What do you think? And how accurate is bmi for you?

    BMI is just a simple number calculation so, by definition, it MUST be "accurate". It's not the number that's inaccurate, it's the interpretation of the number.
  • duffypratt
    duffypratt Posts: 21
    LeBron James has a BMI of 27.5 which puts him solidly in the overweight category. Bodybuilders, carrying 3 to 5 per cent body fat will typically measure as obese according to the BMI scale. That said, there may be health issues that relate to carrying excess mass, even if that mass is lean tissue instead of fat. Gravity, for example, doesn't care that much about what kind of mass it is pulling on.

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