My bf's doc is telling him that he's overwgt, but he's 6'ft 250lbs...he's always been big...they want him to be 200lbs..hes never been that small?

Weight: Unless your boyfriend is a bodybuilder then yes he is overweight. Bmi is only one part of the equation percent body fat is the other just going on the numbers you provided i would have to say that he is overweight. Seek out a physician who is willing to help with a diet and physical activity plan.

Obesity: I understand your feeling for your boy friend. Even though your boy friend has always been big, due to his weight, he is at risk to develop diabetes, high blood pressure, and heart disease. The risk increases if he has high LDL and triglycerides, and has family history of obesity, diabetes, high blood pressure, and heart disease. Please have lab test done for lipid level, and get second opinion.