levothyroxine,hunger,diet pills& coconut oil

Hi I have been on levothyroxine for a while being over 300lbs was a concern of mine.Without asking my doctor I started taking diet pills the green tea kind .I started to lose weight my doctor asked me what I doing I just told him I changed my diet and was eating more salads & soups and I was because I wasn't hungry. With 2nd doctor's visit he showed concern and wanted me to get blood work done. Well I found I couldn't take diet pills but is there something I can use I am trying to stick with my GOOD diet,but with no diet pills it is hard. Also I heard using raw coconut oil could help maybe I don't know I just want find out what to do & not to do THANKS