I'm not a pro at this but i've lost alot of weight with out any diet pills at all and for some odd reason took about month off a while back and didn't gain a pound back. If you've had a good diet and a decent work out schedule it shouldn't hurt you too bad but it might slow down a bit. Diet and excersice teaches your body how to mantain weight/build muscle if thats what your going for. In my opinion diet pills force your body to so once your off them and your body hasn't learned any thing it'll most likely come back.
Push harder today than you did yesterday, push to be stronger today that you were yesterday, push to be faster than you were yesterday, and push to make your best even better, HSFB