Birth Control Options???!?

My girlfriend gained too much weight and became very moody on the pill. So, about a year ago she got the arm implant (bar). This has caused her to bleed very often and it hasn't necessarily stopped. She went back to the gyno and he gave her medicine that stopped it for like 2 weeks, but it is definitely back. She has become overwhelmed by this and wants to seek an alternative. The problem is, she doesn't want to gain weight with summer around the corner and the ring is supposedly a joke...so... Any birth controls known to make sure you dont gain weight? What alternatives does she have? Anything to stop bleeding? ETC!??