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How do we judge a healthy weight range? BMI is no longer valid?

gt5841b
gt5841b Posts: 13 Member
I want to understand how to judge a healthy weight range for myself in order to take opinion out of the equation. What is the standard we are using now? I feel like BMI calculations are dated right? Is body fat percentage the best metric? What is the best measurement tool?
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Replies

  • ninerbuff
    ninerbuff Posts: 48,984 Member
    edited August 2016
    Getting an idea of what your lean body mass is (even if it's off by say 3%), you can get an ideal body weight if you know it and use this formula.

    Your lean body mass divided by (1 minus the body fat percentage you want to be)

    So say you're 120lbs lean body mass and want to be 20% body fat. Then apply the formula.

    120/(1-.20)
    120/.80= 150lbs

    So 150lbs would be the target weight (approximate) to be at 20% body fat.

    A.C.E. Certified Personal and Group Fitness Trainer
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  • amusedmonkey
    amusedmonkey Posts: 10,330 Member
    BMI is a good general indicator. Slightly under or slightly over the normal range is fine. Is your weight within the normal BMI range or close to it? Is your natural waist circumference 80 cm (~31.5 inches) or under? Are you pleased with the way you look?

    If the answer is yes to the above, you are safely within a good range. Are your general health markers within a good range (blood sugar, cholesterol..etc)? If they are not, you may find being at the lower end of BMI more beneficial.

    BMI is not invalid, it's just more valid for some than others. Normal weight is defined as a range not a number for a reason, to accommodate some of that variance among people. Some are still outliers, but not as many as you think and not as many women. For those who are, being at 27 or 17 BMI, for example, and healthy otherwise is a nonissue.
  • sculli123
    sculli123 Posts: 1,221 Member
    For a sedentary person, BMI is OK. For an athlete, it's not really so good. BF% is better, hard to be accurate as already noted but still better than BMI. Then again, the mirror is good enough for me. lol
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
    Dove0804 wrote: »
    I'm not sure where you got most of this information, especially that which I bolded. I think a lot of what you said in your post is a prime example of people in the U.S. (or other overweight nation) having a skewed idea of what a healthy weight is because we are surrounded by overweight/obese people.

    There are quite a few studies demonstrating that those who are mildly "overweight" according to BMI have a lower risk of sudden mortality than those in the "ideal" range. These are very broad studies and any number of factors come into play, such as greater mass provides better protection from injury in accidents, and allows more leeway in unexpected rapid weight loss due to illness.

    There are numerous, numerous health risks that increase as visceral fat increases, and you don't have to fall in the "obese" range for that risk to be increased. No, being overweight is not as bad as being obese health-wise, but having extra, unnecessary fat doesn't do anybody any favors.

    And BMI is not visceral fat. It is a height to weight ratio with no specification as to composition. Also, subcutaneous fat does not carry the same risks for small to moderate increases as visceral fat does. In other words, risk is properly evaluated on a case-by-case basis. Again, the broad studies strictly comparing BMI numbers with health outcomes show no -statistically significant- correlation between having an "overweight" BMI number and the development of health problems... with a caveat that those who are on the higher end of "overweight" and on a trend of weight gain do run counter to the evidence shown by the rest of the group.
    If you are happier being big, that's fine- but don't denounce the BMI scale as being completely bogus because you prefer being that way.

    I denounce the scale as bogus because BMI does not actually measure anything of value, and the ranges assigned to "ideal" and "overweight" do not have an accurately positive correspondence to overall health.

    You have a higher lean muscle mass because you have more weight to carry- yes you would lose muscle as you lose weight, because you wouldn't need it.

    Sorry, I still need it. I'm not a marathon runner or endurance cyclist, nor am I sedentary. My work often requires lifting heavy objects, and so my muscle needs to do quite a bit more than carrying my own mass. It is not a simple one-to-one trade that if I lose 20 pounds of muscle, I can lift and carry something 20 pounds heavier.
    If you were serious about keeping lean muscle mass along weight weight loss, you'd have to do some serious lifting, and then you might end up closer to that of a body-builder with a low body fat percentage. Muscle loss is a fact of weight loss, and it doesn't necessarily mean it's a bad thing. Can you imagine if I, a woman, had the same lean muscle mass at 189 lbs as I did at 260 lbs? That's ridiculous. My body needed more muscle to carry around that weight. That's why most people find it difficult or impossible to carry around, say, 100 lbs of something heavy even though they used to be 100 lbs heavier and carry that around every day.

    Again, this is a matter of weight distribution and the way the muscles and skeleton work together. A 189 pound woman at 20% body fat and the same muscle mass is going to look gorgeous compared to the 260 pound woman at 40% body fat.
    I do agree, and did state, that body fat percentage is a much better indicator. Using your number of <30%- that in no way would be an outlier. An unhealthy BF percentage is often defined, for men, as being above 25%. Average, 18-24%, physically fit as 14-17% and athletes being less than that. I HIGHLY doubt you'd be in danger of being too skinny if you were to be under 185 lbs. I don't believe that for a second. Maybe by your perceptions, but not from a health standpoint.

    Again, BMI is not body fat percentage. BMI is meant to be an approximation of BFP, but it's not usefully accurate for a lot of people and does not distinguish between lean mass (good), visceral fat (bad if too much), subcutaneous fat (less bad if too much) or even water weight. One should never look at the BMI charts to determine their ideal weight, they should look at body fat percentage and their personal appearance and performance goals.

    If I dropped from my current weight to 185 and maintained my present lean mass I would be at 8% body fat. Yes, I expect there will be some muscle loss as I continue to lose weight, but there is no reason I should, or at all want, to lose 20 pounds worth of muscle. There is no health benefit to shedding muscle mass. Yet the BMI charts insist that I would be healthier at a weight that would -require- me to drop 20 pounds of muscle in addition to 55 pounds of fat. (and that's if I settled for 20% body fat instead of 15%),
    Not to mention I would look scrawny and frail.

    On the other end of the spectrum, I also know someone, a petite runner, who comes out as "underweight" on BMI charts, but does -not- look underweight.
    As an estimator of body fat, BMI is most accurate for medium framed, sedentary people. And while that may be the average, there is a large difference between average and mean. BMI is not worthwhile for most individuals.
    Perhaps not coincidentally, it was never developed for individual assessment to begin with. It was an equalization tool to study trends in large populations.

  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
    Hornsby wrote: »
    I used to think just like you, then I surpassed my expectations.

    ETA: at 6'1, you can be 189 without being overweight. Assuming you didn't lose any muscle mass on your way to 189, that would put you at 10%. A pretty ripped individual and still falls in the range of "Normal".

    My goal is to be 220 at 15% body fat. By my calculations, this means I will need to lose around 15 pounds of fat beyond my goal weight and add it back in muscle. In no way, shape or form would being under 200 pounds equate to "surpassing my expectations." I would have to lower my standards to achieve it.

  • Hornsby
    Hornsby Posts: 10,322 Member
    Hornsby wrote: »
    I used to think just like you, then I surpassed my expectations.

    ETA: at 6'1, you can be 189 without being overweight. Assuming you didn't lose any muscle mass on your way to 189, that would put you at 10%. A pretty ripped individual and still falls in the range of "Normal".

    My goal is to be 220 at 15% body fat. By my calculations, this means I will need to lose around 15 pounds of fat beyond my goal weight and add it back in muscle. In no way, shape or form would being under 200 pounds equate to "surpassing my expectations." I would have to lower my standards to achieve it.

    Meh, that depends on how you look at it. Well yea, if your goal is adding more muscle mass (17lbs) then cutting to 10% wouldn't make sense. That depends on one's goals. Which is higher on the totem pole is completely relative. That being said, I'm speaking where you are at now and the notion that you are an outlier.
  • VividVegan
    VividVegan Posts: 200 Member
    If you are female, BMI is good. Body fat % is good and probably the best for both men and women, but it's expensive to get an accurate measurement.

    In my area DEXA scans range from $75-250 each. There's a place nearby that performs 2 for $150 (with a 3 month time gap inbetween) for fitness purposes. Not a bad price if you ask me.
  • 3dogsrunning
    3dogsrunning Posts: 27,167 Member
    sculli123 wrote: »
    For a sedentary person, BMI is OK. For an athlete, it's not really so good. BF% is better, hard to be accurate as already noted but still better than BMI. Then again, the mirror is good enough for me. lol

    @sculli123 - what is an athlete?
    There are tons of recreational athletes that would not fall outside the range.
    For females, it would be even less likely to be outside the range unless carrying a considerable amount of muscle.
    For males who carry a lot of muscle, particularly bodybuilder types - then yea, they would be an exception.

    i agree that some athletes would be an exception but I wouldn't say it applies to only sedentary people.
  • robininfl
    robininfl Posts: 1,137 Member
    Hornsby wrote: »
    I used to think just like you, then I surpassed my expectations.

    ETA: at 6'1, you can be 189 without being overweight. Assuming you didn't lose any muscle mass on your way to 189, that would put you at 10%. A pretty ripped individual and still falls in the range of "Normal".

    My goal is to be 220 at 15% body fat. By my calculations, this means I will need to lose around 15 pounds of fat beyond my goal weight and add it back in muscle. In no way, shape or form would being under 200 pounds equate to "surpassing my expectations." I would have to lower my standards to achieve it.

    That's possible but pushing the envelope on lean body mass at your height, right?

    http://www.builtlean.com/2011/03/30/how-much-muscle-can-you-gain-naturally/builtlean.com/2011/03/30/how-much-muscle-can-you-gain-naturally/

    There is no mandate to be lean or thin, it's YOUR body and aesthetic goals aren't silly, I like the way fashion models look and they aren't at their healthiest possible weight. Also there is no mandate to be the healthiest possible you, nobody does that without being obsessive, and I'm sure even the obsessive are getting it wrong. But there is no exemption from science, either. Carrying more (or less) body fat is less healthy than carrying an ideal amount, this has been conclusively proven. Obesity is the single biggest factor in preventable disease right now, and is in our power to control.
  • JeromeBarry1
    JeromeBarry1 Posts: 10,179 Member
    The weight ranges were determined 240 years ago in France, which was in the midst of the Maunder Minimum famine. With that little historical semi-accurate nugget stated, I'll share that my Dr asked my loss target and I told her it was the middle of the healthy BMI for my height, which is about 160. She suggested that I should go no lower than the top of the healthy BMI for my height, which is about 180. My brother is my height and he's always looked good at about 170.