BMI can be very misleading. If you calculate the BMI of a big muscle guy who doesn't have an ounce of bodyfat it will show him as being overweight. A more accurate, but much more difficult to calculate is your % of bodyfat.
I've got to agree with this. The BMI calculator doesn't take into account muscle mass or body type, and those two things make all the difference! Just using "height" by itself isn't enough information to tell anyone whether they have a healthy body weight. It's a dumb idea IMO.
(I'm writing here about my body when I'm not pregnant.) My normal body weight has always been calculated as "underweight" according to that calculator, but I have a different body type than most other women my height. My hips, for example, are much thinner than most women's hips and my torso is shorter. My best friend is the exact same height as me, but she's got a gorgeous pear shaped figure with a long curvy waist and wide hips and short legs. Compared to her, I have long legs, very thin hips, and an extremely short waist. When we stand next to each other, the top of my hipbones are much higher up on my body than on hers. I believe that both of us have the amount of body fat that we should have, but the hip width difference alone means that I wear a size 2 and she wears a size 6. If she weighed the same amount as me, she'd look grossly thin and anorexic, and if I weighed the same amount as her, then I'd lose my waist entirely and look chubby from the extra fat I was carrying, all because of the differences in our frames. My torso isn't meant to carry the same volume or mass as hers is.
