Gaining a lot of weight

I've got a call from a friend who is now on diet.She is so persevere to be back on her weight before she got her baby.She had a slim body before but now she gained a lot of weight because of pregnancy.Now,she exercise a lot,eat right foods and also she is taking a diet pill too,to have more better result.She even recommended me to try it since I also gained a lot of weight since I got pregnant.I just told her maybe I'll try it after our vacation.