Gained weight in past 5 month, goin to gym 4 days / week, running, weghts. gain only in midse. taking wellbutrin (bupropion) , not pregnant, blood test, thyroid?

Unexplained weight g: Take a look at the stress in your life. If you are doing really high intensity workouts in the gym, that can raise your cortisol and contribute to centripetal obesity (what you are describing). Would also recommend complete thyroid panel with tsh, free t4, free t3, and rev. T3. Wellbutrin (bupropion) shouldn't be doing it, but you can have any side effect on any drug, so if in doubt, talk with your md.