Body Fat vs Body Weight

[WillBrink]

Body Mass Index is only the most crude of fitness tools. It was developed not as a screen for the general population but for demonstrating degree of obesity in the obese. It has value in the bariatric surgery community, not in the general fitness community.

Truth, the problem is, instead of seeing it as the crude screening tool it is, it's been adopted as gold standard by all manner of places and people who should know better and has been a source of real problems and major PITA for all manner of people who can run circles around the dope who just informed them they are obese according to the BMI.

[bsf]

Key term there...The actual accepted margin of error is 3-4%, and tests have shown they fall within that when tested against multi site high end calipers and water. Generally speaking, the leaner you are, the more that margin comes into play, as there's effectively no major difference between being 25% and 28%, but there is say between 9% and 12%.

Accumeasure type calipers are best for tracking actual progress and not bad for actual numbers, but it aint DEXA.


I will say, many years ago when I was asked to write about the accumeasures, I took one look at the cheapo things and fully expected them to be way off from multi site measurements done using reference calipers (Lang medical calipers) by done by an experienced person, and much to my surprise, accumeasure was dead on.

In my n = 1 testing, much lower margin then the 3-4% considered acceptable.

If you are consistent with them in placement, follow the directions, they are accurate enough for "gubment" work and mostly useful for tracking changes.

If one is really dedicated, getting water dunked, or better yet DEXA scanned, to get accurate numbers of BF% within narrower margins is always a good idea, but having known probably thousands the accu-m and or slimGuide tester, and having used them on a lot of people, a very useful, fairly accurate, cheap, device for tracking changes in BF%.

I am entirely satisfied with my purchase. It was cheap, and will work for tracking change.

[WillBrink]

I am entirely satisfied with my purchase. It was cheap, and will work for tracking change.

Exactly.

[murphy j]

Truth, the problem is, instead of seeing it as the crude screening tool it is, it's been adopted as gold standard by all manner of places and people who should know better and has been a source of real problems and major PITA for all manner of people who can run circles around the dope who just informed them they are obese according to the BMI.

Sounds like the Army. I was just informed this last weekend that I'm 24lbs overweight for my age and height. I'm expected to weigh no more than 189lbs and have no more than 24% body fat. I'm 39yrs old and weigh 213lbs according to their scales. The last time I weighed anything close to 189lbs was when I hit 192lbs a couple years ago while working with a trainer. That only lasted a couple weeks then I went back up and hovered around 195-198 for the eight months I worked with him. I really wish people would use this for what it is, not some mythical standard that everyone can attain

[WillBrink]

Sounds like the Army.

Take a look at:

https://www.m4carbine.net/showthread...ti+muscle+bias

[murphy j]

Take a look at:

https://www.m4carbine.net/showthread...ti+muscle+bias

I've read that. I even went back and re-read it. I've seen it both ways, but more often than not it's heavier(muscular) guys that get messed with. I'd love to be a hell of a lot lighter than I am now and maintain stength and endurance, but I haven't figured out a way to make it happen. I just put on weight too easily. I tend to run more than anything else right now because that's always been the most difficult thing for me. Mainly trail running nowadays. Diet is a big issue with me too. Due to conflicting schedules and just generally being busy alot, my wife and I don't eat together much and it's usually eat what's laying around or hit some sort of fast food. Pizza is a big weakness for me.

[Dos Cylindros]

I do detest the BMI as it does not provide a realistic measure of physical fitness, especially for those who regularly participate in physical excercise.

Obviously the BMI is most out of whack when you use it on people like NFL and NBA players along with boxers as most of them are huge, carry alot of muscle mass and are generally genetic freaks (all respect due). However I do feel, that the average joe dismisses the BMI out of hand without doing some real soul searching. Weight lifters are the ones I see as the most guilty. Just because you can bench 500, or squat 800 does not mean you are physically fit. Most guys, not all but most I know who can do these feats are carrying alot of extra body fat, and have little or no cardio capacity at all. If they lost some of that body fat they would be alot closer to an ideal BMI (which also goes to show that body fat % is far more important than the BMI).

I am in no way supporting the BMI, but if you don't engage in regular excercise and a decent mix of cardio and strength training and you are fat by BMI standards, guess what..........your still fat. Don't say the BMI is not realistic because people like this don't fall intothe category of people I would say are the exceptions to the BMI. The BMI is a guideline, not a great one, but better than nothing for the sedentary people of the world.

[murphy j]

The BMI is a guideline, not a great one, but better than nothing for the sedentary people of the world.

But it's being used as the standard for everybody and it's not 'one size fits all'. I'm also far from sedentary and have always had trouble meeting the BMI. Even when I weighed 155lbs in Basic/AIT I carried a large percentage of body fat. Just to give you an idea of how hard it is for me to lose weight/body fat, my weight never wavered more than 3lbs the whole time I was in Infantry Basic/AIT. So while the BMI is used, it's not taking in to account that individuals vary a great deal.

[Dos Cylindros]

But it's being used as the standard for everybody and it's not 'one size fits all'. I'm also far from sedentary and have always had trouble meeting the BMI. Even when I weighed 155lbs in Basic/AIT I carried a large percentage of body fat. Just to give you an idea of how hard it is for me to lose weight/body fat, my weight never wavered more than 3lbs the whole time I was in Infantry Basic/AIT. So while the BMI is used, it's not taking in to account that individuals vary a great deal.

Totally understand, and totally agree. I was just pointing out that is can be a very rough measuring stick to see how far out of line someone might be.

[WillBrink]

Totally understand, and totally agree. I was just pointing out that is can be a very rough measuring stick to see how far out of line someone might be.

In the general non athletic population as a crude screening tool, yes. Adopted to athletic populations, and ignoring actual BF% and performance, no. Problem is, that's exactly what has happened.