Men are supposed to be bigger than women

[Eryn]

that's part of the problem, with male BMI I'm underweight, but with female weight I'm in the ideal range. I also fail to see why men and women have different dietary needs, and I suspect it's men's diets that are causing the male gender to die soon than women. Women generally take better care of their body not only through diet but are far more willing to see a doctor them men generally are I think men could learn alot from women in this respect.

I think that you've got it sussed. BMI is a statistical construct based upon a wide range of people and has little meaning for individuals. I'm 6'2" and 165 and felt that getting under 160 wasn't right for me. My father had a larger bone structure and would have been underweight at 165. If you have a small bone structure you might well be fine at 150. How do you feel and look? If bones are sticking out like a heroin chic model then you might have a problem, otherwise you're likely fine.

Statistically, men tend to have more bone mass and a greater muscle/fat ratio than women. Muscle is denser than fat, so men will weigh more than a woman of the same girth.