BMI seems like a wrong/bad goal?
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LumberJacck wrote: »LindaMc6262 wrote: »BMI seems to be off mathematically. The relationship between height and weight depends on volume and density. Density is body composition, which is ignored. Volume is three dimensional. The BMI formula uses weight / height squared. Shouldn't a cubed measurement be used instead? I think this is part of the reason short and tall people may get inaccurate weight ranges.
In my case, I find the upper BMI limit for my height extremely high. I'm 5'2" with a very small frame. According to BMI, 136 is "healthy." I am obviously heavy at that weight. Even now, at 119, I need to lose a bit more. I looked best at 110.
I ignore BMI and go by my own experience, the mirror, and how I feel. I'm just lucky I'm in the range so I'm not harassed by anyone in the medical community. I'm sorry large framed muscular people have to deal with that. Doctors should know better.
You are right. BMI uses square power, but actually the power should be about 2.5, which is why there is a "newer" BMI calculation that uses 1.3 times your weight divided by height to the power of 2.5. You can read about it here http://www.bbc.com/news/magazine-21229387
i doubt this is any better than the old method. seems like someone just grasping for a new formula. makes a difference of 2 pounds for me in either direction which throws me just to be in the normal range now vs underweight before.0 -
LumberJacck wrote: »LindaMc6262 wrote: »BMI seems to be off mathematically. The relationship between height and weight depends on volume and density. Density is body composition, which is ignored. Volume is three dimensional. The BMI formula uses weight / height squared. Shouldn't a cubed measurement be used instead? I think this is part of the reason short and tall people may get inaccurate weight ranges.
In my case, I find the upper BMI limit for my height extremely high. I'm 5'2" with a very small frame. According to BMI, 136 is "healthy." I am obviously heavy at that weight. Even now, at 119, I need to lose a bit more. I looked best at 110.
I ignore BMI and go by my own experience, the mirror, and how I feel. I'm just lucky I'm in the range so I'm not harassed by anyone in the medical community. I'm sorry large framed muscular people have to deal with that. Doctors should know better.
You are right. BMI uses square power, but actually the power should be about 2.5, which is why there is a "newer" BMI calculation that uses 1.3 times your weight divided by height to the power of 2.5. You can read about it here http://www.bbc.com/news/magazine-21229387
That doesn't seem to address the issue of body composition, as it still uses the same two measurements. Two people of the same height and weight with different body compositions would have identical BMIs, regardless of the math, if height and weight were the only two inputs.
To actually adjust for composition, there would actually have to be volume measurements involved. And once you are doing all those measurements, you might as well just estimate body fat% instead, if health and fitness are what you are trying to determine.0 -
LumberJacck wrote: »LindaMc6262 wrote: »BMI seems to be off mathematically. The relationship between height and weight depends on volume and density. Density is body composition, which is ignored. Volume is three dimensional. The BMI formula uses weight / height squared. Shouldn't a cubed measurement be used instead? I think this is part of the reason short and tall people may get inaccurate weight ranges.
In my case, I find the upper BMI limit for my height extremely high. I'm 5'2" with a very small frame. According to BMI, 136 is "healthy." I am obviously heavy at that weight. Even now, at 119, I need to lose a bit more. I looked best at 110.
I ignore BMI and go by my own experience, the mirror, and how I feel. I'm just lucky I'm in the range so I'm not harassed by anyone in the medical community. I'm sorry large framed muscular people have to deal with that. Doctors should know better.
You are right. BMI uses square power, but actually the power should be about 2.5, which is why there is a "newer" BMI calculation that uses 1.3 times your weight divided by height to the power of 2.5. You can read about it here http://www.bbc.com/news/magazine-21229387
i doubt this is any better than the old method. seems like someone just grasping for a new formula. makes a difference of 2 pounds for me in either direction which throws me just to be in the normal range now vs underweight before.
A typical consumer scale isn't even accurate to 2 pounds.
Perhaps a refresher on the meaning of the word "guideline" is in order....
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I use it for no other reason beside remembering what weight is considered officially underweight for me, for funsies.0
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This can't be right. The overweight rate in Canada was about 33% in 2013 (less than 1% change since 2003) and obesity 18.2% (less than 4% increase since 2003). The people in this report must have been overstating their obesity. Although, yes BC is the place to be with 14.3% obesity (up less than 3% since 2003) 30.7% (.1% change since 2003) overweight - better weather in the more populated areas, so easier to exercise?. Newfound and Labrador- whoa! 29% obesity (up over 8% since 2003) - economic conditions? Stats Can is a fun playground...
http://www12.statcan.gc.ca/health-sante/82-213/index.cfm?Lang=ENG
I cited a reliable source too but I agree the numbers don't seem right. I'm thinking the map is using another scale.0 -
This can't be right. The overweight rate in Canada was about 33% in 2013 (less than 1% change since 2003) and obesity 18.2% (less than 4% increase since 2003). The people in this report must have been overstating their obesity. Although, yes BC is the place to be with 14.3% obesity (up less than 3% since 2003) 30.7% (.1% change since 2003) overweight - better weather in the more populated areas, so easier to exercise?. Newfound and Labrador- whoa! 29% obesity (up over 8% since 2003) - economic conditions? Stats Can is a fun playground...
http://www12.statcan.gc.ca/health-sante/82-213/index.cfm?Lang=ENG
I cited a reliable source too but I agree the numbers don't seem right. I'm thinking the map is using another scale.
This might be a dumb question, but by "self reported" do they mean that the subjects provided their height and weight rather than being weighed in "officially", or whether they identified themselves as overweight or obese?
If it's the latter, than change should aways be understated because each person is to some extent going to be comparing themselves with others to determine their status. If everyone gets bigger, the average moves and the weight that seems "normal" will move with it.0 -
MakePeasNotWar wrote: »This can't be right. The overweight rate in Canada was about 33% in 2013 (less than 1% change since 2003) and obesity 18.2% (less than 4% increase since 2003). The people in this report must have been overstating their obesity. Although, yes BC is the place to be with 14.3% obesity (up less than 3% since 2003) 30.7% (.1% change since 2003) overweight - better weather in the more populated areas, so easier to exercise?. Newfound and Labrador- whoa! 29% obesity (up over 8% since 2003) - economic conditions? Stats Can is a fun playground...
http://www12.statcan.gc.ca/health-sante/82-213/index.cfm?Lang=ENG
I cited a reliable source too but I agree the numbers don't seem right. I'm thinking the map is using another scale.
This might be a dumb question, but by "self reported" do they mean that the subjects provided their height and weight rather than being weighed in "officially", or whether they identified themselves as overweight or obese?
If it's the latter, than change should aways be understated because each person is to some extent going to be comparing themselves with others to determine their status. If everyone gets bigger, the average moves and the weight that seems "normal" will move with it.
i would assume they provided their height and weight. wouldn't make sense otherwise.0 -
MakePeasNotWar wrote: »This can't be right. The overweight rate in Canada was about 33% in 2013 (less than 1% change since 2003) and obesity 18.2% (less than 4% increase since 2003). The people in this report must have been overstating their obesity. Although, yes BC is the place to be with 14.3% obesity (up less than 3% since 2003) 30.7% (.1% change since 2003) overweight - better weather in the more populated areas, so easier to exercise?. Newfound and Labrador- whoa! 29% obesity (up over 8% since 2003) - economic conditions? Stats Can is a fun playground...
http://www12.statcan.gc.ca/health-sante/82-213/index.cfm?Lang=ENG
I cited a reliable source too but I agree the numbers don't seem right. I'm thinking the map is using another scale.
This might be a dumb question, but by "self reported" do they mean that the subjects provided their height and weight rather than being weighed in "officially", or whether they identified themselves as overweight or obese?
If it's the latter, than change should aways be understated because each person is to some extent going to be comparing themselves with others to determine their status. If everyone gets bigger, the average moves and the weight that seems "normal" will move with it.
Yes, you're correct. It isn't a dumb question at all, by the way, curiosity should never be apologised for.
Self-reported means participants share what they feel like. When it comes to weight, even when it is supposedly anonymous, it is fair to assume that numbers might be too low. And even with 100% honest test subjects, there will still be differences in height and weight measurements due to non-standardised equipment, etc.0 -
Makepeas, I checked back on the link provided, and here's the source of the data:
Source: Public Health Agency of Canada (2011); using 2009–2010 data from the Canadian Community Health Survey (Statistics Canada).
This was their collection method:
http://www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey&SDDS=3226
It's a random sampling of Canadians. The self-reporting would be whatever the survey responder recorded.
The questions are pretty thorough for height and weight.0 -
"Self-reported" has to be one of if not THE biggest problem with most of the diet studies.0
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