BMI is bunk.

silverpig

Lifer
Jul 29, 2001
27,703
12
81
At the beginning of the year I was 6'3" and 206 lbs. I look pretty healthy, although I'm a little soft in some spots. Anyways, this yields a BMI of just over 25.

According to fitday.com that put me in the "overweight" category. 200 lbs is the border between healthy and overweight for someone who is 6'3". I've been hitting the gym and am down to 194 or so now so apparently I'm now a healthy weight.

Now, I'm aware that BMI doesn't scale well for heavily muscled athletes, but how about for a regular guy like me? According to fitday.com a guy who is 6'3" is considered to be healthy all the way down to 148 lbs. 148! I'd be a freaking skeletor if I was 148 lbs. I mean, the blue tights and purple hood would be kinda neat, but then I'd have He-Man on my ass all the time, messing with my stuff.

Doing a bit of googling, it seems that fitday is just going with the standard BMI scale:

BMI Categories:

* Underweight = <18.5
* Normal weight = 18.5-24.9
* Overweight = 25-29.9
* Obesity = BMI of 30 or greater


6'3", 148 lbs = BMI of 18.5. BS that's healthy. To be pegged right in the middle of the normal weight section, I'd have to weigh 174 lbs. Since reaching this height I have weighed that much once. I hit the rowing training extra hard for 2 weeks, didn't up my intake of food and water and became very sick and dehydrated. I lost a lot of weight over 3 days and had trouble leaving bed. I weighed myself, saw 174 lbs, then did nothing but eat and drink water and milk for the next day until I felt better and was back up to 190 lbs.

Also, don't the units seem kind of weird? kg/m^2... that's mass per area. I bet there's a better unit of measurement just by looking at the dimensions.

Disclaimer: This is not a discussion about fitness or health, but of the scale used to determine such.
 

Newbian

Lifer
Aug 24, 2008
24,779
882
126
Wait... you gained 16 pounds of weight in one day with nothing but water and milk? :Q

 

RichardE

Banned
Dec 31, 2005
10,246
2
0
Easy math...

Grab your belly..

If you can come up with a handful of fat and still have more fat to grab, you need to lose weight :p
 

JDawg1536

Golden Member
Apr 27, 2006
1,275
0
76
Man, Abraham Lincoln was getting trashed in Vegas for his 21st birthday when the BMI was invented. It's useless, don't sweat it.
 

silverpig

Lifer
Jul 29, 2001
27,703
12
81
Originally posted by: Newbian
Wait... you gained 16 pounds of weight in one day with nothing but water and milk? :Q

No no. There was tons of food too. A lot of it was just lost water weight though.

But yeah, I put on 16 pounds in 1 day. I lost the same amount in the 3 days previous. I was NOT in the best of health at that time :(
 

ric1287

Diamond Member
Nov 29, 2005
4,845
0
0
yeah 6'3" here too and i always laugh imagining myself at 150 as a "healthy" weight. I do also cry a little inside when I'm placed in the "OMG you're going to die of obesity" range.
 

jagec

Lifer
Apr 30, 2004
24,442
6
81
BMI works fine for a rough idea of "proper" weight using commonly available measuring devices (do YOU have a body fat meter at home?). Nothing wrong with heuristics.

I'm 6'2", 160lbs, and I don't look like a skeleton. If I was much thinner, I would.

Try traveling sometime, you'll see lots of people in the "normal weight" range who look just fine. BMI works perfectly well for the majority of people on the planet. Like any back-of-the-envelope calculation, it shouldn't be considered to be any sort of absolute standard.

I honestly don't know why this concept is so difficult to understand...
 

Mo0o

Lifer
Jul 31, 2001
24,227
3
76
BMI is more useful at a population level to calculate epidemiology stats

On a person to person basis it's only a very very rough estimate.
 

Fayd

Diamond Member
Jun 28, 2001
7,970
2
76
www.manwhoring.com
Originally posted by: silverpig
Originally posted by: Newbian
Wait... you gained 16 pounds of weight in one day with nothing but water and milk? :Q

No no. There was tons of food too. A lot of it was just lost water weight though.

But yeah, I put on 16 pounds in 1 day. I lost the same amount in the 3 days previous. I was NOT in the best of health at that time :(

yeah..3 days of explosive diarrhea and vomit will do that to you :(

(been there...only had 2 days of it, though. guess i was lucky.)

my BMI = 35.3. i'm a porker :(

fwiw, i always thought BMI sucked as a measurement. how do you account for people who are 240+ lbs, but all muscle?
 

CycloWizard

Lifer
Sep 10, 2001
12,348
1
81
kg/m^2 because it's more or less a specific surface area deal (mass/area ~ volume/area). The bigger this number gets, the more spherical you must be, right? It's either that, or BMI is not useful for this at all. I'll vote for the latter.
 

silverpig

Lifer
Jul 29, 2001
27,703
12
81
Originally posted by: CycloWizard
kg/m^2 because it's more or less a specific surface area deal (mass/area ~ volume/area). The bigger this number gets, the more spherical you must be, right? It's either that, or BMI is not useful for this at all. I'll vote for the latter.

Maybe, except if you did mass/volume and computed density, then you'd have something more akin to fat content. Perhaps there's a better exponent to use, such as mass/height^2.5 or something.

Maybe someone should go out and do some statistics, then calculate a fit line.
 

KeithTalent

Elite Member | Administrator | No Lifer
Administrator
Nov 30, 2005
50,231
118
116
Mine is 21.5, not that it means anything at all.

KT
 

Fenixgoon

Lifer
Jun 30, 2003
33,680
13,406
136
Originally posted by: Mo0o
BMI is more useful at a population level to calculate epidemiology stats

On a person to person basis it's only a very very rough estimate.

ftw. much better used across the population than for individuals. after all, some athletes will have very high BMI's due to all their muscle, but are in unbelievable physical shape.
 

vi edit

Elite Member
Super Moderator
Oct 28, 1999
62,484
8,345
126
Originally posted by: Fenixgoon
Originally posted by: Mo0o
BMI is more useful at a population level to calculate epidemiology stats

On a person to person basis it's only a very very rough estimate.

ftw. much better used across the population than for individuals. after all, some athletes will have very high BMI's due to all their muscle, but are in unbelievable physical shape.

Exactly. It's a population measurement, not specific demographics. If you walk through a hospital I can almost guarantee you that every person in there with a BMI over 30 is indeed fat, not muscle bound.

And even still, if you are a muscle bound person with a BMI of 30, you still are at risk. It's just that much more mass that your heart and vascular system has to account for and pump blood through.
 

rivan

Diamond Member
Jul 8, 2003
9,677
3
81
Originally posted by: ric1287
yeah 6'3" here too and i always laugh imagining myself at 150 as a "healthy" weight. I do also cry a little inside when I'm placed in the "OMG you're going to die of obesity" range.

I'm 6'5" and have 34.4 bmi. I could stand to lose about 30 pounds to ditch the gut, but 255-260 is my "right" weight, no matter what BMI tells me (260 would still be 30.8 bmi).

So yeah, BMI is full of it, for me.
 

judasmachine

Diamond Member
Sep 15, 2002
8,515
3
81
I'm 5'8" and 139lbs. and my BMI is 21.1 which seems about right, very little body fat, and no large muscle mass...

 

hanoverphist

Diamond Member
Dec 7, 2006
9,867
23
76
Originally posted by: RichardE
Easy math...

Grab your belly..

If you can come up with a handful of fat and still have more fat to grab, you need to lose weight :p

quicker test... look down. see your shoes? youre good.
 

actuarial

Platinum Member
Jan 22, 2009
2,814
0
71
Originally posted by: hanoverphist
Originally posted by: RichardE
Easy math...

Grab your belly..

If you can come up with a handful of fat and still have more fat to grab, you need to lose weight :p

quicker test... look down. see your shoes? youre good.

Or your cock.

That way you're either skinny, or hung like a horse so......you're good!