Is BMI an accurate way to know how much I should weigh?
Replies
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My experience differs from yours. I live in Canada, i've visited 10+ gyms and it's very common to see really muscular people. I started lifting really young and i've seen the progress of many young lifters, it didn't take long for them to build a considerable amount of muscle mass. Yes they lift heavy and eat a lot of food, but it's really not that difficult.
In general, we have lower levels of obesity particularly morbid obesity.0 -
Gaining muscles while young is relatively easy, even if it's just 10-15lbs of muscles it's enough to put you “slightly” out of the normal range. Meaning a bmi of 26-27.
That assumes they [apparently a man, based on your reference to testosterone] started with average or better muscle mass for a man already, and one gains faster if one is new to lifting. The idea that any man who adds 10-15 lb of muscle mass must be out of the normal BMI range doesn't make sense.
I would agree that waist to height or calipers or other BF estimates are good supplements IF you think that you are at a good weight above the normal BMI, but it seems like way more people assume they don't fit the normal BMI, even when they are still well above it, than is likely.
Mostly I don't get why this is some huge topic. If an individual thinks it doesn't fit them, there are certainly ways to estimate body fat, and in any case being somewhat into the overweight but not obese range when otherwise active and with no negative test results tends not to be a health issue statistically (with this varying based on ethnic background).5 -
I'm talking about the average man, I speak in generalities. It's not an absolute statement.
Also the point is why go straight to bmi instead of using other measures that are just as valid?0 -
frankwbrown wrote: »
Yes. Here is a comparison:Theoldguy1 wrote: »Have you compared a DEXA scan to the Withings scale? We have an older scale and it isn't worth the powder to blow it to hell regarding getting a reading similar to DEXA scan.
A = Withings Body+ (9/30 at 6:10 am);
B = DEXA scan (9/30 at 11:30 am)
body fat: A = 49% , B = 44.5%
weight (lb): A = 304.9, B = 305.0
fat mass (lb): A = 150.8, B = 135.6
lean mass (lb): A = 154.1, B = 169.4 (159.9 excluding bone mass)
water mass (lb): A = 125.8, B = n/a
bone mass (lb): A = 7.6, B = 9.5
BMI: A = 40.4
Bioelectrical impedance isn't that accurate, especially when only feet are involved (vs feet and hands).
I use it primarily to confirm that I'm losing fat mass and not lean mass.
Some doctors at Cedars-Sinai developed an alternative to BMI. It's called Body Fat Mass Index.
Relative Fat Mass Index:
Men: 64 – (20 x height/waist circumference) = RFM
Women: 76 – (20 x height/waist circumference) = RFM
https://www.cedars-sinai.org/blog/relative-fat-mass.html
So - since we've digressed the bejeepers out of this thread already - why not: What result does the RFM calculation yield, for you?
I'm curious, because the result it gives for me - especially if I measure my "waist" at just above the top of my pelvic bones as directed in the article, rather than at natural waist - is . . . improbable, IMO. I understand that the article says RFM is "roughly equal to your body fat percentage." Maybe they define "roughly" differently than I do?
I'm as capable as the next person of having pleasant delusions about my body composition, but the "Navy calculator" says 23%, BIA scale says 23.3%, visual (my own biased eyes, photos like those on an earlier page in the thread) would be mid-twenties % (high teens upper body look, 25-30 lower body look, roughly), BMI 20.6.
RFM, using natural waist = 29. (OK, maybe that's roughly roughly. Very roughly.)
RFM, using top of hip bone as instructed in article = 34. Huh?
I'm not truly bizarre in body geometry, either, I swear. Definitely within the range of normal human females.3 -
I'm talking about the average man, I speak in generalities. It's not an absolute statement.
Also the point is why go straight to bmi instead of using other measures that are just as valid?
The OP is female. It is highly unlikely she is so muscular that she is a bmi outlier. She is not able to put on muscle mass in the manner you have been suggesting. You can't generalize from young men to a woman of unknown age.9 -
frankwbrown wrote: »
Yes. Here is a comparison:Theoldguy1 wrote: »Have you compared a DEXA scan to the Withings scale? We have an older scale and it isn't worth the powder to blow it to hell regarding getting a reading similar to DEXA scan.
A = Withings Body+ (9/30 at 6:10 am);
B = DEXA scan (9/30 at 11:30 am)
body fat: A = 49% , B = 44.5%
weight (lb): A = 304.9, B = 305.0
fat mass (lb): A = 150.8, B = 135.6
lean mass (lb): A = 154.1, B = 169.4 (159.9 excluding bone mass)
water mass (lb): A = 125.8, B = n/a
bone mass (lb): A = 7.6, B = 9.5
BMI: A = 40.4
Bioelectrical impedance isn't that accurate, especially when only feet are involved (vs feet and hands).
I use it primarily to confirm that I'm losing fat mass and not lean mass.
Some doctors at Cedars-Sinai developed an alternative to BMI. It's called Body Fat Mass Index.
Relative Fat Mass Index:
Men: 64 – (20 x height/waist circumference) = RFM
Women: 76 – (20 x height/waist circumference) = RFM
https://www.cedars-sinai.org/blog/relative-fat-mass.html
So - since we've digressed the bejeepers out of this thread already - why not: What result does the RFM calculation yield, for you?
I'm curious, because the result it gives for me - especially if I measure my "waist" at just above the top of my pelvic bones as directed in the article, rather than at natural waist - is . . . improbable, IMO. I understand that the article says RFM is "roughly equal to your body fat percentage." Maybe they define "roughly" differently than I do?
I'm as capable as the next person of having pleasant delusions about my body composition, but the "Navy calculator" says 23%, BIA scale says 23.3%, visual (my own biased eyes, photos like those on an earlier page in the thread) would be mid-twenties % (high teens upper body look, 25-30 lower body look, roughly), BMI 20.6.
RFM, using natural waist = 29. (OK, maybe that's roughly roughly. Very roughly.)
RFM, using top of hip bone as instructed in article = 34. Huh?
I'm not truly bizarre in body geometry, either, I swear. Definitely within the range of normal human females.
It's almost as if this suggests that ANY one metric can be off for a certain percentage of people (or can be mismeasured by some people) and it's best to consider several and think critically about the ones that give unexpected results.
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and even most muscular fit young men are not far out of BMI range - a point I made earlier.
This 'but young muscly men disprove BMI charts' seems nonsense to me.
Yes they may be slightly out of range - ie have BMI of 27 ish, but unlikely to be well over the range unless elite bodybuilder or some obvious outlier.
rather than vague unsubstantiated claims of "many men I know" - test this theory against known men of known statistics.
For example Kyle Hartigan - I realise most of you will never have heard of him but I chose him because he has been the full back for AFL football team I follow and his stats are public record.
Full back is not the most running position so fair to assume he will be less lean runner type and more strength body type than other players.
Also fair to assume professional sports players are fit and do gym work as well as general training.
He is 194 cm tall and weighs 98 kg - gives a BMI of 26
Anyone can do this excercise with any sports player whose stats are easily found on google6 -
Also - context
Yes young fit muscly men can have BMI sightly over the range and not be carrying excess fat. if you are such a one and have a BMI of 27 ish - Highly likely this is so.
Post menopausal asian woman (hypothetical example) who does little activity with BMI of 27ish - highly unlikely.
Paper pudding -real life example. 50 year old woman lightly active and no gym work.
I'm sure both my doctor and myself and any casual observer could see my then BMI of 28 was not due to outlier level of muscle mass or any other exceptional reason - but plain old overweight.5 -
I wasn't talking about very muscular men, I gave a conservative exemple of someone who put on 10-15lbs of muscles. I already said after a year OR MORE you can gain more than that.
Also what is the threshold for someone to be well over the range of healthy bmi?
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yes - and i gave a real life example, and explained my rationale for that example. it is easily checked via google, unlike vague unsubstantiated "many people I know"
feel free to do likewise.
I have no idea how much muscle someone could realistically put on - but still highly unlikely they will be far out of BMI range by doing so.
not sure what point you are making really.5 -
Repeating: OP is female.
The fact that a minority percentage of muscular young men can be at an ideal weight at something over the normal BMI range is of limited relevance. (I strongly suspect it's a minority percentage, i.e., less than 50%, but I can't prove it.) **
The thread is not about muscular young men, insofar as the OP defines the topic.
Do any other old people hear faint strains of something by Carly Simon? 🤣 (Nah, JK.)
** Fun slideshow about NFL players who lost weight after their playing careers, fuel for both fires burning here, in a sense:
https://thesportsdrop.com/20-nfl-players-that-lost-a-ton-of-weight/
"After" BMIs of those players, men who are selected to be huge in the first place, and do their professionally-guided utmost to add muscle mass (and some fat mass, while playing, i.e., eat in a surplus), though they are not of course bodybuilders; those not labeled are overweight BMI:
ETA: To me, some of the "after" look like they still have some fat they could lose, though most look pretty lean even at the higher BMIs; some at the low end look maybe a little excessively lean . . . but that's JMO in both instances2 -
I could give my own exemple but I don't know if it's good enough for you, after 2 and a half years of weightlifting I was 17% body fat at a bmi of 28. That's not elite bodybuilder status.
That fullback is ok but he's not that muscular. He's tiny compared to the average fullback in the NFL that's for sure. The average NFL FB is 5'11 215ish pounds.
Edit : Actually that was for running backs, fullbacks are even bigger at 6'1 245lbs on average.
Also i'm just replying to people who quote me or bring up that topic, I have moved on personally.0 -
still not sure what you are disputing mellouk
- so you were a young muscly male with a BMI of 28 - yes, young muscly men can be slightly above BMI range and be at a healthy weight. No disagreement there, Ive said exactly that myself.
But, unless they are elite body builders or suchlike they are not going to be far outside the range - if we look at real top level sportsmen with known verifiable stats, we can see that
Nothing special about the one I used as an example - my explanation of position he plays was just to show I have not cherry picked a lean running midfield type and it isnt a matter of being 'good enough for me' - I chose an example that is verifiable by everyone via simple google - just like stat's Ann posted..
and anyway none of that relates to OP's question - she is not an elite bodybuilder nor a sporty young man and it is highly likely her ideal weight will indeed fall somewhere in the standard recomended BMI range.
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Wait - 20 lbs of muscle added in a year or longer.
Even for a young man - he ain't gonna add only muscle if he's maxing his gains like that, there will be fat added.
So I wouldn't be surprised if these healthy young men that are all over the place gaining muscle that fast and being in BMI overweight range- are indeed carrying more fat than perhaps desired, maybe even more than could be healthy. There are plenty of power lifters with plenty of muscle - and plenty of fat.
I'm sure they are well outside healthy BMI range - and from the size of many a gut - that BMI figure should cause a pause and look if that's healthy overall. Sure more muscle pushes them over, but just visualizing many that have fat pushing them over too.9 -
I've enjoyed reading the comments here. It's been entertaining.
I suspect that people who have a problem with BMI are those that fall outside the range. Telling them they're not far outside the range doesn't help. Who doesn't want to be considered "normal/healthy"? And BMI is no help to these people (like myself) when we are trying to set a goal weight for ourselves.
I laugh when I see baseball caps advertised as "one size fits all". I wear a size 62 cm hat. Thanks for telling me I don't count. Some are starting to say "one size fits most" (truth in advertising, thank you).
A lot of sites that have BMI calculators give the ranges and imply that your BMI accurately categorizes you in one of those ranges. Again, false advertising: "one size does not fit all."
If you're happy with BMI, great. But please don't tell me it is a better indicator of body health than all the other alternatives. Or that it isn't perfect, but it is sufficient. (BTW, I'm not accusing anyone of saying that)
I must admit, I'm perplexed that some people react negatively to the suggestion that measuring more than height and weight (e.g. circumference of neck, waist, hips...) might provide a better metric, as if that can't be more accurate.
So in conclusion, BMI -- just like your typical baseball cap -- does not work for me. And to monitor my health, I want information about fat mass, lean mass, bone mass, and VAT (visceral adipose tissue). Additionally, I want information about my cardiovascular fitness.
But to each his own.
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did anyone say it was a better metric than any of the alternatives?
I might have, in terms of easy DIY calculations (waist measurement is that too, DEXA scans and the like not so much)
Not sure what you mean by "BMI doesnt work for me" - if you mean you want other information too ,then sure, thats up to you.
If you mean the standard BMI recomendations, taken in context, do not apply to you - well, yes, I would be disagreeing with that.5 -
I think the point that seems to keep getting glossed over is that BMI is just one of many markers...2
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I don't think anyone is saying BMI is the one and only measure. What people are saying is that if you are a healthy fat percentage above the BMI normal range, this typically will not be a shock to you -- you will be aware you have more muscle than normal and thus that BMI might not fit. Also, if you are above the BMI normal range and think that's not true given your own perception of your size (even without being someone who has spent time gaining muscle or who has an occupation likely to build muscle), there are additional ways to check to see if you really are over bodyfat (unfortunately the most accurate of which are expensive, but things like waist to height and waist to hip can be helpful too).
But as an initial check or general range for someone losing and well above the BMI, it's usually a good place to start.
Some seem really anti BMI, and it usually seems like it's those who think they don't fit. I don't really get that (again, if you are significantly more muscled than average, of course BMI doesn't fit, but that's not common, as theoldguy keeps saying, even though as I understand it he himself is above the BMI range because of a lifetime in the gym). In particular, if one is well above the BMI range, it makes more sense to worry about the appropriate goal weight closer to that weight, and very often people seem to think the range is crazy and then change their mind as they lose.
OP is a woman, as others keep saying. I don't think she should "obviously freak out" or whatever she initially said, just for being overweight by BMI, but I also don't think the answer is "who cares, BMI is stupid." I'd ask how much she's over the normal range and what other accessible and free measures indicate.6 -
I feel like reminding one more time - OP is female. Whether or not BMI can be misleading for young men focused on building muscle is decidedly off topic.
Personally, I think it's arguable that many under-40 men working on building muscle have a low enough bf% while falling outside the healthy BMI range, but it has absolutely no bearing on the OPs question. Due to women's essential bf level being higher, it is highly highly unlikely that a woman above the healthy BMI range has a healthy bf level.
As most of us have said, while there is no need to panic, she has probably gotten a needed wake up call. Unfortunately, she hasn't been back to the thread. Hopefully after posting, she decided to start minding her calories and get more active. A realization I think many of us have had to come to at the tail end of this year 6 -
I could give my own exemple but I don't know if it's good enough for you, after 2 and a half years of weightlifting I was 17% body fat at a bmi of 28. That's not elite bodybuilder status.
That fullback is ok but he's not that muscular. He's tiny compared to the average fullback in the NFL that's for sure. The average NFL FB is 5'11 215ish pounds.
Edit : Actually that was for running backs, fullbacks are even bigger at 6'1 245lbs on average.
Also i'm just replying to people who quote me or bring up that topic, I have moved on personally.
That's also not particularly lean for a male...17% BF for a male is a good amount of fat that, if which lost, would probably put you at the higher end of BMI.
I also don't know what elite athletes like NFL running backs and fullbacks has to do with a normal female posting on MFP...it's not like we have a world of elite football players running around being mistaken for being "overweight"8
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