BMI is actually an inaccurate way of measuring whether you are over/under/ or about the right weight. This is because it only really considers a person's height and overall weight, it does not take into consideration your type of body, bone type--large, heavy boned, regular, or light, delicate bone structure, etc. It also doesn't differentiate between muscle weight and fat weight. Muscle weighs more than fat, but is good. Fat which weighs less than muscle is bad. So any measuring method that only uses height and overall weight is not capable of giving an accurate result as to whether someone is over/under/ or about the right weight. You could take two people the same height and weight, with one being an athlete, one fat, but because of the difference in bone structure and the difference in weight between muscle and fat, both can appear to be overweight, when in fact, the athlete is in absolutely top shape.
There are a number of other weight measuring systems that are more accurate than the BMI system. Check out this link for more on them:
http://bmi.emedtv.com/bmi/bmi-for-athletes.html
Bioelectrical Impedance seems to be the most sensible method. Underwater weighing sounds somewhat unrealistic to me, but maybe I just don't get the science involved. I feel the same way about using calipers to measure the difference between the belly fat and the thighs. That one is like the BMI. It doesn't take enough other factors into account, so it sounds phony to me. Personally, I would stay away from Dual-energy x-ray absorptiometry (DXA) and Computerized Tomography, as DXA uses X-rays and CT is a CAT scan, which uses very high, and unsafe doses of radiation. It's best to use safer alternatives that don't use radiation whenever possible.
So if you really want a more accurate measure of whether you are over/under/ or about the right weight, never mind the actual pound and oz numbers, or for that matter, the inaccurate BMI scale. Go with something like Bioelectrical Impedance, or as a back up, maybe the underwater system.
It really isn't a matter of how much you weigh. It's a matter of how healthy you are--that is, do you exercise, eat mostly healthy, and get enough sleep. If you do all that you should be okay, whatever your weight is, and remember, muscle weighs more than fat, but muscle weight is good, so if you have worked up some muscles that will also affect how much you weigh.
Now stop fretting, get some exercise, eat healthy, and get some sleep. (Now, if only I can follow my own advice! )
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau