Wednesday, July 15, 2009

To BMI or Not To BMI

My money is on Not to BMI. While for a certain body type person this may end up being an accurate calculation of obesity level, for the vast majority of people it is most definately not. I have believed for a very long time that a much more accurate measure is Body Fat %. The main problem with BMI as I see it is the logic behind the math is fundamentally flawed. The formula is based purely on weight and height, but what about those muscle builders? Since muscle is heavier than fat, if a person is in athletic or really fit shape, their weight will be higher thus their BMI higher, putting many of these people in the overweight or even obese category. What? Seriously? You're going to try and convince me that, for example, Mr. Olympia 2008 Dexter Jackson is Obese? At 233 lbs and 5' 6" his BMI is 37.6 putting him high into the Obese range. The case is similar with all the Mr. Olympia's.

Now, how are we, the average overweight person trying to get healthy, supposed to use this measurement to get us healthy? If we do too much muscle building, it bumps our weight higher so that even if we get down to the size we want to be, we'd still be overweight by BMI standards. So, maybe we don't build so much muscle, but that's what burns the calories so that we can lose the body fat. And what if we let our muscle mass shrink? Well, do you think the scrawny person who can't lift a gallon of milk is better off than someone who has so much muscle mass it boosts their BMI into Overweight or Obese? I sure don't. There has to be a happy middle in which we can build the muscle we need or desire, reach our size goal, and are still considered healthy. There is! It's called Body Compositon. This is a method for determining how much by percentage, of your body is Lean Mass (muscle, bone, organs), and how much is Body Fat. That is a much more accurate determination of overall health and risk levels.

Why don't we do this? Quite simply, BMI is fast, easy and cheap. Body Composition is not. I firmly believe this is holding us back, and I vow from this moment on not to look at, calculate or even consider BMI as a determinig factor in my healthy living efforts. While I may not be able to go through the fancy body composition testing, just usung a scale that measures body fat, or having a trainer at your gym measure with a scale or some calipers, is way more accurate. I'll stick with that.

Remember, weight loss and healthy living is a personal journey. No one can tell you how to make that journey or what path to take or not take. I suggest listening to what people have to say, soak in the advice and the articles, then make your own decisions. Come to conclusions that are right for you. You know your body better than anyone else!

Healthy and Happy Living


Bella said...

I think for the average person BMI works pretty well, though obviously there is such a thing as skinny-fat (someone who is thin but has a too-high fat percentage). And for athletes and body builders - well, it explicitly states that the BMI cannot be used for those people (just like it can't for pregnant women). I don't think that the average person who is trying to lose weight will ever reach that point though, that they will end up having a BMI that is considered overweight because of their muscle mass.
So basically, I do not think that a BMI tells it all, but it is an easy way to see if you are overweight or not. Because if your BMI is over 27 and you are not an athlete or bodybuilder, you most likely are. (And I am pretty sure athletes and bodybuilders know their exact body composition and don't care about BMI as they know it isn't valid for them, so in the end it all works out for everyone.) I also disagree that it is holding us back (well, at least it isn't holding me back), because to me it is common sense that you also have to work out to be fit and healthy.
As for the scales that measure body fat, as far as I know they can be pretty inaccurate.

a_healthier_me said...

Bella - always happy to have a differing point of view. I'm not saying that BMI is wrong for everyone, I think my problem with is more on the professional side (such as doctors and insurance companies using it) then on the personal side. As an individual you know your body, you know how much muscle you have, you know when you are fit and feel good - insurance companies (for example) don't take that into consideration, at least not the ones I've talked to.
If the BMI measurement works for you, great. Go for it! It doesn't work for me and my body type. Because of my lean muscle mass, if I got down to a "healthy" body mass, my Body Fat % would be in the "Under Fat" range. Which is probably why I have more of an issue with BMI.

And yes, I do know that many of the scales can be inaccurate for measuring body fat, especially because how hydrated or dehydrated you are can drastically skew the numbers. Nothing is going to be a perfect measure for everyone. I personally prefer BF%, but am putting more stock in how my clothes fit and the inches I lose than anything.

Whatever gets you healthy and helps you reach your goals is right for you!

Moms Fighting Fat said...

Good Morning, I don't like BMI but I agree with Bella in that it's a good tool for we "regular" people. Often times I think even regular people who are on a fitness routine use "muscle gain" to flippantly. It takes a long, long, long time to build a pound of muscle and you actually have to consume more than the daily intake of calories and eat tons of protein. That's not to say we can't achieve lean muscle mass though, however, it's not going to have that much of a difference with weight.

However, I agree that you should go with what works for you. Lately, the BMI calculators I've seen are a bit more thorough, they ask for neck, waist, hip, and wrist measurements--plus height and weight.

I LOVE, LOVE, LOVE your site! I saw your post on the SITS roll call this morning and had to drop by--you'll be seeing me again. :-)