"i started phentermine in 2015 weighing in at 300lbs. within 2 weeks i was down 13lbs but one of the horrible side effects was insomnia. i decided to step up my workout regimen and take only a half of pill and ended up losing  a total of 45lbs in less than 5 months. once losing the weight, i got pregnant and gained it all back so now i&#039;m taking it again in hopes of getting the weight off a second time. i suggest drinking a lot of water and working out that will make the weight come off faster. although this pill was effective for me, i suggest talking to your doctor first."