It’s hard to imagine how such a finding could be news to anyone who knows much about weight and fitness, such as those that designed the study. BMI has never been anything but a gross measure, to give a general idea of appropriate weight.
Any personal trainer worth her salt will tell you that what really matters is not BMI. BMI can be skewed by muscle mass. Since muscle is much denser and heavier than fat tissue, those with lots of heavy muscle will have an elevated BMI, but still be super fit.
I remember last winter olympics looking at the body weight of the female hot dog skiiers. These women, at the extreme of fitness, weighed much more than a similar, non-athlete woman of the same clothing size. The same holds true of any athlete. By BMI standards, they will be overweight, or even obese!
So what’s a better metric? You may already know. Body fat. Body fat, while still a somewhat crude metric because the margin of error of most ways to measure it is 2-4% points, tells a much fuller story. So if you want to get into the nitty gritty of your fitness level, go to a gym and have your body fat measured. And have a workout there while you are at it! Then, if you set a fitness goal, set it around body fat % rather than BMI. That way, if you lose fat and gain muscle, but the scale doesn’t change, you will know your are still increasing your fitness.
Here’s a link to the Wall St. Journal article that reports on the study: http://online.wsj.com/article/SB10001424052748704762904575025313433081780.html#
What’s the net-net of all this? Scales and BMI only tell part of the story, and could even be downright misleading. Plus, the scale accounts for an awful lot of angst and obsession.
Focus instead on feeling really good in your body, each and every day by eating to feel good over time, and exercising to get a feel good buzz all day long. :)