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21 Dec 2004

True BMI Calculation
Hi,

I am 29 yrs old, 167cm tall and currently weigh 82 kg. This gives me a BMI of 29.4...putting me in the "nearly obese" range(>=30). For me to get to a BMI of less than 25..(to be out of the "fat" range), I will need to weigh approx. 69kg.

I estimate am carrying about 7kg of extra weigh at the moment and estimate that a weight of between 73-75 would be ideal...however this still has me in the "fat range of the BMI calc. If I were to weigh 69kg I would be extremely thin (I weighted 69kg when I was about 16). I have done extensive paddling and cycling when growing up and therefore have bigger shoulders and thighs than the average guy.

Is there a better weigh of calculating your ideal weight which factor in more than just your height and weight?


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Expert
FitnessDoc
fitnessdoc

01 Jan 0001

Hi Fred

Unfortunately, you are one of the ones against whom the BMI does discriminate, and you are quite right in saying that it is not reasonable. Having said that, the only way to know for sure that your weight is made up of muscle and lean tissue and not fat (which is essentially the problem that BMI is trying to address) is to have a full range of body composition tests done. These are often inaccurate (the skinfold calipers) and often expensive (Xray type machines). What these tests would do is to show you exactly how much fat you have, how much muscle you have and how much bone mass and that would resolve the argument.

As for BMI, it is a contentious measurement. The problem is that if you measure say 1000 people, you can pretty much be sure that most of them will fit quite nicely into the equation and be satisfied by it. However, if you then introduce someone with more weight training or exercise in their history, they fall outside the "normal" range of people (in that group of 1000) and so the equation falls flat. That's just an unfortunate thing at this stage. What I can assure you of is that research is being done to overcome this problem. Often, insurance companies are looking at BMI as a health marker, and so we are really trying hard to educate people that BMI alone is not the way to tell and then prescribe rates on. That is something in the not too distant future, in case that is your concern. However, for now, if you can't have these full tests done, I guess that the best is to just be satisfied in your physique - if you believe that you have 7 kg to lose, then go for it, and don't get too hung up on the numbers of it all. At the end of the day, all you can do is exercise and eat well and whatever happens must happen anyway.

Good luck
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