BMI is a joke

rdzilla

As many have said the BMI is a guideline for the average person with the average build. Anyone with some weight (fat, muscle or both) will instantly be overweight or obese. At 308 pounds I weigh a lot and, trust me on this one, it isn't all muscle. At my goal weight of 240 pounds I'm still going to beconsidered obese for a 6'2" male according to BMI calculations. In college we had a true body composition done as part of our athletic program and mine came up as 228 pounds of muscle and I weighed in at 265-270 pounds at the time or ~15% body fat. If I can somehow get to my goal weight it should be the best that I've ever felt and I, nor my Scandanavian genes and bone structure, care what BMI has to say about it.

"Bad Misleading Information" => LOL

kunibob

Yeah, while my case isn't =as extreme, 0% body fat would still put me in the healthy BMI range...riiiight. :S It is a guideline and not an absolute rule, for sure. You will probably notice a decrease in lean mass as you continue to lose weight (I had a small decrease even with weight training + consuming lots of protein), but I doubt it will be anything near 30 lb worth! % body fat is a FAR better indicator.

Allasauna

This is just off wikipedia:

The body mass index (BMI), or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing "social physics".[1] Body mass index is defined as the individual's body weight divided by the square of his or her height. The formulae universally used in medicine produce a unit of measure of kg/m2. BMI can also be determined using a BMI chart,[2] which displays BMI as a function of weight (horizontal axis) and height (vertical axis) using contour lines for different values of BMI or colors for different BMI categories.

While the formula previously called the Quetelet Index for BMI dates to the 19th century, the new term "body mass index" for the ratio and its popularity date to a paper published in the July edition of 1972 in the Journal of Chronic Diseases by Ancel Keys, which found the BMI to be the best proxy for body fat percentage among ratios of weight and height;[3][4] the interest in measuring body fat being due to obesity becoming a discernible issue in prosperous Western societies. BMI was explicitly cited by Keys as being appropriate for population studies, and inappropriate for individual diagnosis. Nevertheless, due to its simplicity, it came to be widely used for individual diagnosis, despite its inappropriateness.



It goes on some more but the point is that its not a very accurate way to measure someone's health. Its just a simple guideline. If your BMI comes out high and you do not seem to be very overweight, then an accurate measurement of your percentage of body fat should be taken to determine if and how much weight you could/should lose.

shakybabe

according to wii fit mine should be 22 and I'm 24. something, but body fat scales give a different reading and a different BMR thats higher than what MFP gives me!.. (though it also gives me a different weight too). It's annoying they were the most expensive scales but get no where the same weight on them as my other bathroom scales or wii which are all around the same number.

As 3 out of 4 are the same I go with the number that's been given by 3 of them! According to the body fat scales though my body fat was consistently going down and lean muscle mass up, when I got them I was loads lighter on them (up to a stone difference some times) now I find I'm getting heavier readings on those and lighter on all the others, it makes no sense!!!

manjingirl

Firstly congratulations on your weight loss so far. You must be pleased, I know I would be.

With regard to BMI - you cannot take your current estimate of lean body mass and assume that it will be the same or similar when you lose the desired amount of weight. You will lose some lean mass, even if you eat well, exercise and do all the right things. Your muscles will not need to move so much weight around, your bones won't need to support the weight, you won't have the same blood volume etc.

BMI is a guide only and is an indication for your risk of developing several weight-related health problems like diabetes, arthritis, heart disease amongst others. BMI is pretty good for most people except very muscular men, and occasionally very very muscular women.

EricMurano

BMI for me is a tricky thing. I don't completely understand it although I do think that its a fat vs muscle ratio more than anything.

I was told by someone that you do need some fat but its the "good" fat that you need not the "bad" fat. But I still don't understand what he's actually talking about, but I do know that I think its impossible to have absolutely NO body fat and all muscle.

its just my opinion

Your body needs some fat to stay alive. There's two "places" where fat is stored on your body. Subcutaneous fat and visceral fat.

Subcutaneous fat is the fat under your skin. It's the fat you 'see' in the mirror
Visceral fat is the fat that's in between your organs.

You needs ome visceral fat because it cushions your internal organs. If you have very low body fat and you fall over or contort your body in a weird way you might injure your organs.

Body fat also plays a big part in hormone regulation. Ever hear or women whose periods stop when they get very lean? This is because of this hormone thing.

Women need more fat on their bodies than men do. That being said women at their healthy body fat percentage will look really slim so don't get so caught up on the number.

EricMurano

Firstly congratulations on your weight loss so far. You must be pleased, I know I would be.

With regard to BMI - you cannot take your current estimate of lean body mass and assume that it will be the same or similar when you lose the desired amount of weight. You will lose some lean mass, even if you eat well, exercise and do all the right things. Your muscles will not need to move so much weight around, your bones won't need to support the weight, you won't have the same blood volume etc.

BMI is a guide only and is an indication for your risk of developing several weight-related health problems like diabetes, arthritis, heart disease amongst others. BMI is pretty good for most people except very muscular men, and occasionally very very muscular women.

Very good points

downsizinghoss

I am 5'10''. It is a standard set of tables (which is why it isn't always very good). One place you can check it is under the tools tab on this site.

ElizabethRoad

I don't know why everyone complains about BMI being inaccurate. It was never meant to be used on individuals. It's like saying that your screwdriver is a joke because it doesn't hammer very well.

Acg67

To fit in the BMI scale my body fat percentage would have to be ZERO. I weigh 205 not counting the fat. No way I could physically reach 174.

As it is unfortunately I am in the 420's now at 51% body fat. But since I used to be 530 I will take it.. for now!

You are making the assumption that you will have no muscle loss while dieting, which is an incorrect assumption

lglg11

I dont have much advice on BMI .. I'm learning alot by reading this thread so thanks for starting it ..


I did want to say Congrats on the loss so far ! Thats incredible . No matter what any numbers say (scale , BMI , etc)
keep moving forward and stay motivated . You must feel awesome!

MinnesotaManimal

To fit in the BMI scale my body fat percentage would have to be ZERO. I weigh 205 not counting the fat. No way I could physically reach 174.

As it is unfortunately I am in the 420's now at 51% body fat. But since I used to be 530 I will take it.. for now!

You are making the assumption that you will have no muscle loss while dieting, which is an incorrect assumption

AC is most likely correct, you would have developed a pile of muscle to be able to move around all the extra weight. And as far as I know, there is no way to lose body weight without losing SOME muscle, but if you eat plently of protien, lift heavy weights and lose your weight slowly, you have the potential to be a hell of a strong guy at a reasonable body weight when your done.

downsizinghoss

That also depends a lot on how much I lift though. I have always been a big guy. They did the water displacement test on me 20 years ago and my lean mass was 230. I have actually lost a lot of muscle mass when I stopped working out (and just getting older). My long range goal is to add back 10-15 pounds of muscle mass.

ahinescapron

A professor that I had who is an exercise physiologist basically told me that BMI is useless, especially for anyone who is muscular or athletic. The program I was in was full of athletes (I was very athletic at the time) and basically everyone in the class fell above their ideal range according to BMI, even though we all had very low body fat. It is basically just quick and dirty math, because measuring body fat is more difficult. I don't trust it or go by it, because I know for a fact that it is not accurate for me.

castadiva

BMI is used by medics and insurance companies, among others, because it is cheaper to do some simple maths than to invest in proper technology to accurately assess individuals. The charts currently in common use were devised at a time when large parts of the population were malnourished (in the aftermath of WW2), and have been adjusted downwards several times since to account for the inclusion of typically-smaller non-European races as the World Health Organisation has expanded its' reach and data. This arbitrary scale was never intended to diagnose individuals, but rather to measure average populations.

Even as a guideline, this scale is not appropriate, especially for those whose genetic background consists of nationalities where greater-than-average height and a large build is typical (most of Scandinavia, Germany, large parts of Eastern Europe and Scotland are examples that come to mind). To highlight the absurdity, an article I read yesterday in The Guardian (UK National Newspaper) had this to say: "on current BMI definitions George Clooney and Russell Crowe are clinically "obese" while Brad Pitt and Mel Gibson are "overweight".
http://www.independent.co.uk/opinion/commentators/dominic-lawson/dominic-lawson-dont-believe-obesity-figures-ndash-theyre-spun-for-a-purpose-912216.html

Russellb97

To fit in the BMI scale my body fat percentage would have to be ZERO. I weigh 205 not counting the fat. No way I could physically reach 174.

As it is unfortunately I am in the 420's now at 51% body fat. But since I used to be 530 I will take it.. for now!

You are making the assumption that you will have no muscle loss while dieting, which is an incorrect assumption

Yes, and that LBM isn't 100% muscle.
Water and glycogen, among many otthers are counted as LBM.
For example I'm a "spiker"so the day before I spike my glycogen is drained and my weight could be 200lbs, say I have 20lbs of fat. so I'd be at 10% bodyfat. Now when I spike, I gain 5lbs of water weight by restoring glycogen. So no my weight is 205lbs, but fat mass is still 20lbs. but now my BF% is 9.8%. I didn't gain 5lbs of muscle, but i did gain 5lbs of lean body mass.

EricMurano

BMI is used by medics and insurance companies, among others, because it is cheaper to do some simple maths than to invest in proper technology to accurately assess individuals. The charts currently in common use were devised at a time when large parts of the population were malnourished (in the aftermath of WW2), and have been adjusted downwards several times since to account for the inclusion of typically-smaller non-European races as the World Health Organisation has expanded its' reach and data. This arbitrary scale was never intended to diagnose individuals, but rather to measure average populations.

Even as a guideline, this scale is not appropriate, especially for those whose genetic background consists of nationalities where greater-than-average height and a large build is typical (most of Scandinavia, Germany, large parts of Eastern Europe and Scotland are examples that come to mind). To highlight the absurdity, an article I read yesterday in The Guardian (UK National Newspaper) had this to say: "on current BMI definitions George Clooney and Russell Crowe are clinically "obese" while Brad Pitt and Mel Gibson are "overweight".
http://www.independent.co.uk/opinion/commentators/dominic-lawson/dominic-lawson-dont-believe-obesity-figures-ndash-theyre-spun-for-a-purpose-912216.html

The sad thing is that insurance companies would know that BMI is not a good metric for assessing a single person's health. The thing is they are all about statistics. They don't care if you yourself have higher lean body mass; they just need a quick, cheap and easy metric to plug into their algorithm for deciding how much of a risk you are. For most of the people they sell insurance to the BMI will be an acceptable metric to use. The insurance companies are not going to care if they over charge athletes, body builders and just generally healthy people because they just don't make up the majority of the population.

downsizinghoss

To fit in the BMI scale my body fat percentage would have to be ZERO. I weigh 205 not counting the fat. No way I could physically reach 174.

As it is unfortunately I am in the 420's now at 51% body fat. But since I used to be 530 I will take it.. for now!

You are making the assumption that you will have no muscle loss while dieting, which is an incorrect assumption

Yes, and that LBM isn't 100% muscle.
Water and glycogen, among many otthers are counted as LBM.
For example I'm a "spiker"so the day before I spike my glycogen is drained and my weight could be 200lbs, say I have 20lbs of fat. so I'd be at 10% bodyfat. Now when I spike, I gain 5lbs of water weight by restoring glycogen. So no my weight is 205lbs, but fat mass is still 20lbs. but now my BF% is 9.8%. I didn't gain 5lbs of muscle, but i did gain 5lbs of lean body mass.

These are good points. I have never put much stock in the BMI number I just had to post last night because I found it humorous how the scale compared to my personal reality. My lean body mass was 205 and BMI said 209 would be obese.

One reason I did the bod pod was the sheer number of times I have been asked by people/trainers/doctors/nosy people "What is your BMI?" I recommend having the survey done for anyone that is trying to become more fit.

bcattoes

You will lose muscle mass along with the fat.

downsizinghoss

and for those that have congratulated me on the loss so far.. THANK YOU! I came to MFP to break past a plateau and the tools and the people have been a great help!

I have been public with the process for over a year now and the support has been pretty rocking. check out www.facebook.com/downsizinghoss if you are so inclined.