Ms. addictive personality here. I think I've tried almost all of them. Most of them made me feel like crap. Very jittery, upset stomach you name it and sometimes I ate more instead of less!
I have however used the Alli with success. You must follow the diet recommendations tho. If not, be prepared to never be more than 2 seconds away from a toilet! It does help tho and doesn't have any of the jitery crapy side effects.
As far as your friend being a weight loss buddy, I'm thinking your gut is right and you should just hang out. If your gonna have a buddy you need to be on the same page otherwise it gets very frustrating for you.
As for the Acai, they are full of anti oxidents which is good. I never had any adverse affects but I don't know that it helped either. You'll have to let us know.