bone structure

You can have small, medium or large body frame (which can be calculated by measuring your wrist or elbow). If you have large frame calculate your normal BMI by adding 10% to the numbers that are used by calculators. If your frame is small you have to substract 10%. BMI is also only relatively accurate for medium height, if you are shorter or taller than average, your numbers are also off. I have large frame, so even though I still have some weight to lose, I am not aiming for lower range. And I will never be size 2 either.

As for skinny, statistics does not support this theory either. People with low BMI do not live longer, and are not healthier. Anyway it is statistics, we are individuals, and when applied to one person statistics does not work. We all need to try to take good care of ourselves, but weight by itself is not a good measurement of health. Lots of people unfortunately lose weight when in poor health. We are so concerned with losing weight, that sometimes do not even realize that there are lots of people on this site who are tracking their calorie intake to gain weight or make sure they do not lose more.