I'm confused. I used an electronic hand-held device that supposedly measures both body fat and BMI. My body fat according to the device, is 20.5, but my BMI is 29.1, which according the the scale I was looking at, puts me real close to being obese. I'm not anywhere near obese to look at me, so what am I to deduce from this instruments calculations? Is the instrument faulty?

My wife got me one of those types of devices about a year ago, and it was saying my BF was 23%, let me just say it was having "convulsions" in inaccuracy.

Yes, they are faulty.

These types of devices are not accurate. Nor are BMI calcultors on the net you see. There are several specific personal particulars that these do not account for, and thus are extremely inaccurate.

I get my BF checked through DEXA, which can also do BMD (Bone Mass Density, and other things). I do trust this system, I dont think we can get it "exactly" right, but we can get close, and for me DEXA is close and very accurate.


ROCK ON


Chillen

" deduce " that BMI does have some inherent weaknesses and, as a result, may be very misleading at times.

The basic problem is that BMI doesn't distinguish between muscle tissue and fat. That's why BMI is a poor measure of your health, fitness or ideal weight....and is likely why this BMI score is close to ' obese ' in your case. Body fat % is much much better tool IMO.

Body builders and other jocks / hard-core gym rats carry a lot more lean body mass than the average person. If they used the BMI, they might be likely be classified as overweight. Same problem with someone who isn't lean. Someone could have a "healthy" BMI and yet have a ridiculously high level of body fat....overfat in other words, you can be seen a having " skinny " body type/ frame ...and yet still be carrying a lot of body fat.

At best, BMI is more of a broad and general measure of health risk but it's prone to the bogus assessments of overweight but not overfat and normal weight but overfat.

BMI is a straightforward calculation based on your height and weight.

The device probably measured your BF% using the electrical resistance method. This assumes that fat is more resistive than muscle. However, bone is also more resistive than muscle, so the assumptions about bone mass may not be accurate for you (some such devices have "athlete" modes to try to tune the bone mass assumption).

While BMI is useful for population studies, since most high BMI people are overfat, it may be inaccurate as a measure of health status for a highly muscular individual. Muscle is quite dense and heavy, so a person who is not overfat may have a high BMI that is normally considered overfat or obese (e.g. body builders).

It is, however, possible for someone to be highly muscled and overfat at the same time. If your body fat is 20.5%, your BMI is 29.1, and you are male, that may indicate a lot of muscle, but also a little more than a desirable amount of body fat (but not anywhere near what is normally considered the obese level). If your body fat really is 20.5%, you likely have a significant amount of flabby stuff around the abdomen (perhaps sitting on top of and hiding some six-pack abs).

I think you hit it on the head. I do have some "flabby stuff around the abdomen" that I'd like to get rid of and I'm working on it. Of course, that hot fudge shake I had this afternoon probably didn't help much. Also, at age 48, 20.5 percent is within the good category for body fat. I'd still like to get down to around 15%.

Thanks all of you for your comments.

BMI is a useless number. if you are short and lean, with a lot of muscle, your BMI will show you're morbidly obese.

if you are really tall, with little muscle mass, and a big beer gut, your BMI might be 'ideal'.

BMI is nothing but a height to weight ratio type calculation. it doesn't take into account the body fat percentage or muscle mass.

the mirror, and a skinfold caliper bodyfat test are the way to go.