BMI… does it mean much? Misleading? Good basic info/guideline?

“Frankly I am more than a little bemused that is is causing so much fuss.”

whoa. Calm down there Bruce. Everything we discuss here on BPL is really ” a tempest in a teapot” using your own language.

FWIW my BMI is 20.2. My cholesterol ratio is the best my doctor has ever seen and my BP is 124/65. I wasn’t looking for an out.

i just found it an interesting subject.

I guarantee I can find someone with the same BMI that can’t even do a single pullup or pushup properly. In fact, most people with “normal” BMIs can’t.”

I would speculate with considerable confidence that there are a very large number of people with BMIs in the low 20s who couldn’t match your performance metrics across the board.

“I think we should be measuring ourselves in terms of what we can do, not what numbers we have. I’d like to lose weight because it will allow me to do what I love to do even better…but at the same time, I don’t feel my “overweight” BMI stops me one bit.”

+1 If I were to be searching for metrics to assess my health, I would be looking at blood work, BP/RHR, and possibly a stress test Those, in combination with an honest assessment of diet and exercise, would tell me what I needed to know. My BMI is in the neighborhood of Kat’s, but there is no way I would consider myself fitter than Craig based on it. And I’m in a position to know whereof I speak on that particular subject.

I think BMI is a good example of something that is useful for evaluating an overall population, but not so good on an individual level.  I believe a relevant concept would be that of ecological fallacy.

If I were to go to my closest shopping mall this weekend and choose 1000 people. and measure their BMI, I am fairly confident that for 90% of those the BMI index says are overweight, they will agree that they could afford to lose some weight.

To reference one study comparing BMI vs DEXA or densitometry, it found that about 7-8% of people were misclassified as obese using BMI, while about 41% of men and 32% of women would be misclassified as non-obese.

-J

Did BMI ever claim to be definitive in terms of measuring overall health? It’s one of a number of measurements which, combined, still wouldn’t tell the whole story. But what’s the alternative?

Numbers don’t judge us. They’re an aid, perhaps, towards getting a picture of our health (think, cholesterol). Unfortunately, we tend to judge ourselves, or others, based on these numbers.

Your cholesterol score may look bad based on genetics. People who eat well and are active can be condemned by themselves or others for simply inheriting a gene. Same with BMI. All of this has to be factored in.

Our society in particular rewards certain body types. Careful, or your genetic type might be next!

Some seem to miss something that was raised here, which is that people with “good numbers” on paper can end up fooling themselves as being in good/great shape when they are in fact not. This thread is more about that than giving anyone with not-so-good- numbers a hard time. I brought this up because my numbers are in fact very good but I know I could be much healthier.

BMI is more of a general guideline; it doesn’t take age, physical characteristics, conditioning, muscle mass, visceral fat and other items into consideration.   One really needs to look at their BMI number and look at themselves in the mirror and evaluate what you see with respect to BMI and determine what’s appropriate as a general guideline.   My observation is most people who have high BMI numbers typically are in the overweight or obese category. Sure, anyone can point out exceptions within the parameters, or any other defined healthy parameter, but one really needs to look at themselves along with other health indicators and determine where they are with respect to being healthy.  In other words if you starve yourself and never exercise and have a low BMI, you should realize that the low BMI has nothing with being healthy.  On the other hand if you’re in the BMI overweight range and don’t have a lot of muscle mass there’s probably some likelihood the BMI chart is in fact somewhat correct.

For me, I fit the BMI charts almost exactly.  At 6’-2”, during hiking season I’m typically at 165, right in the middle of the healthy range at a BMI of 21.  If it’s a long hike I’ll exit with a BMI of 20.  But starting about the time Halloween candies hit the shelves and the end of the year let’s just say my BMI level definitely creeps up!

I think it’s sad that we’re in a day and age where people cling to some sort of random figure rather than be honest with themselves.

Mental illness and eating disorders aside there is not a person on this planet that doesn’t know if they fat, skinny, fit, unfit.

The whole purpose of BMI in my opinion is so doctors can make quick sweeping generalisations about the state you are in without getting you to take your top off, get their hands dirty or take too much time out of their day.

You can use calipers and the skin fold method as a fairly easy and fairly reliable method of fat %, it’s reconed that you can get a +/- 3% accuracy of how much fat we’re carrying.

Does a particular figure really matter though?

I don’t believe so, i know when i’m fat, i know when i’m not as fit as i’d like, a figure doesn’t really change or help that.

Even something as simple as how clothes fit gives a good indication, if your diet and exercise level hasn’t changed much yet your clothes are starting to feel baggy (or even tight) then you should visit your doctor as both can be signs of something more serious than BMI.

But even then body fat percentage is not in any way a indication of how fit someone is, if it was then Heroin and Meth addicts would be clearing up the medal table at the olympics.

Some of the most unhealthy athletes i’ve come across are competitive body builders, they look buff and toned, but the toll of getting “competition fit” takes on them both mentally and physically is terrible.

Makes me sad that all this “self help”, “you can be anything you want as long as you set your mind to it” nonsense has now become the norm, folks feel like they can’t get through life without having certain goals, i’ve seen time and time again people set a certain weight as a goal, problem is once that goal has been reached most folks just move onto something else or pat themselves on the back then fall back into the same ways before they tried losing weight, as the regime they set themselves to reach said goal is not sustainable for the rest of their lives.

The cross section of people on BPL is probably not the sedentary, overweight or obese, processed food eating couch potato in industrialized countries.

Hang out at your local mall and observe the obviously poor lifestyle of most shoppers.

BMI is a good starting point for most Americans. My BMI hasn’t changed much during my adult life although my fitness level has changed from time to time… key point being I don’t have much body fat.

I am not a doctor..be it the MD or PhD type.

But I do know that what seems to be a good rule of thumb across the board is that your waist size should be half your height or less. Better put as the Weight to HeighT Ratio  (WHtR)

For moderately well educated types. Like an office IT worker who writes outdoor blogs:

http://www.telegraph.co.uk/news/health/news/9260091/Forget-BMI-just-measure-your-waist-and-height-say-scientists.html

for the better educated MD or PhD types:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4223160/

Looking back at my weight over the years (unemployed and skiing almost every day at my best, burnt out office worker a couple of years ago at my worse,  to my present condition of less-burnt out office worker who is able to walk everywhere during the week) one thing has been consistent: I am at my best shape when my waist size is lower.  

Sounds like a “No sh**” statement.

And it is.

But many people look at BMI,  the scale,  try to figure out body fat percentage using formulas, etc etc.

I know I did.

Not being an MD or PhD type, I know it is just a rule of thumb.

But it is a rule of thumb that I think is more useful than BMI.  And probably more accurate overall.

At my most in shape every a few years back when I was skiing so much and light weight training, I was 168 lbs on my 5’6″ frame.  But with a 32″ waist.  My BMI was 27 according to charts and I was overweight :)

I’m almost back to where I was a few years ago. Don’t know the weight as I don’t own a scale anymore. But I do know my waist size…and the WHtR.   Getting there.

The WtHR is similar to BMI. It doesn’t indicate how fit a person is. Let’s say we have an out of shape and overweight person who is 5’10” and 210 lbs. Via diet only they can get down to 150 or even 135 lbs. Via mostly running (a lot) they can get down to the same weight. Obviously the second scenario will be a much fitter person. But all things considered, whichever way a person got there, they are probably going to be much healthier.

I think mark nailed it.  We have things like bmi and food pyramid because we want to lie to ourselves.  We know if we are fat.  Just like we know what healthy food is.

we use all these other things and doctors as a way of attempting to fool ourselves.

i have a severely over weight sister and she has to very over weight boys.  They eat no vegetables at all.  Pretty much just processed carbs and fake cheese.

The doctor told her not to worry about their weights, they will grow into it.  Both of them are perpetually congested in their chests, doc wants to remove tonsils.  No one ever tells her to diet, to eat real food.  If it’s not a drug or procedure they never talk about it.

When talking about people who have a low BMI but are not healthy, you have to look at the alternative.  Before BMI people just talked about there weight and a lot more people can get swept up in a false sense of security when just talking about weight.  BMI was created, in part, to correct for that so that everyone no matter how tall they were could be compared on a single scale.  Someone 5’2″ and 10 lbs overweight means a lot more than someone 6’2″ and 10 lbs overweight.

When talking about people who have a low BMI but are not healthy, you have to look at the alternative.  Before BMI people just talked about there weight and a lot more people can get swept up in a false sense of security when just talking about weight.  BMI was created, in part, to correct for that so that everyone no matter how tall they were could be compared on a single scale.  Someone 5’2″ and 10 lbs overweight means a lot more than someone 6’2″ and 10 lbs overweight.

Sweeping generalisations like BMI simply do not work in a vast majority of cases though Ben, plus there have been far more reliable methods out there for a fair few years now (skin fold, caliper, method as an example).

Saying it’s better than the alternative is like saying “i only stole a car, i saw someone robbing a bank on TV so thought it’s not as bad as that” it’s no real defence.

All joking aside it’s a system that’s absolutely pointless, if people learn how to be honest with themselves then it wouldn’t even be needed.

I think it’s also worth repeating that having less body fat doesn’t in any way-shape-or-form mean someone is fit, or fitter than someone that’s a bit fatter but exercises.

It’s absolutely no indication of how long someone is likely to live either, lifestyle and genetics pay a far more crucial role in that.

It’s a shame that society has gotten to the point of political correctness that people can’t even be honest with themselves, as the expression goes “know thyself“