Really worried about my brother, needs serious help?

Okay so my brother is almost 20 years old and I am 18. Through his life he never had many friends, was over weight, and got made fun of at school. This started at a young age. He was always a closed off person, not showing much expression except for anger, and he never wanted to talk about his emotions. Then, a couple months ago, he came to me and told be that he has extream anxiety and depression. I knew this all along becuase he never made friends, always stayed inside in the basement and played video games ALL day. I knew he had been unhappy, but he never wanted to talk about it. SO we went to the doctor and he got put on depression pills and pills to help him sleep. He said they are helping, but he is not changing. He might feel better on the inside but he stil acts the same. Never does anything but watch t.v. and play video games, doesnt meet people, work out, or anything. He recently ran out of the pills he is taking and he is very nervous without them. I dont want him to be so reliant on them. I want him to find the fullness of life without pills, but he claims they are really helping. I can see why he is depressed, becuase he doesnt do anything with his life and i have told him that many times.Me and my mother have tried so many times to tell him to start working out and meeting people but he just doesnt do it. Me and my mother cry and worry about him everyday and i would give anything to make him happy but he isnt doing anything about it. I want his life to have meaning, i want him to have a girlfriend and friends but i am loosing hope. What should i do?