I think it is a withdrawl. I was taking it regularly for 3 months and was taking 1 full 37.5 pill a day, towards the end I was taking 1-2 more because my body was so used to it. I had stopped before for a few weeks and had no major issues other than being tired and ravenously hungry all of a sudden, but it passed after a week. When I stopped recently, it was like someone hit me with a sledgehammer - headache, extreme exhaustion, major hunger. Fortunately I was prepared for it, and I did have a few pills left, so I ignored the hunger as best I could and have been tapering off with 1/2 - 1/4 a pill a day. Today is my last day I have had a half only. I think I may have a 1/2 left, which I may split up between tomorrow and SUnday. I think this is the only way to stop, if not to prevent the horrid fatigue, but to prevent eating everything in sight. Anyway, taper off slowly, people say that constantly on this site but man, it is so true...dont want to gain that weight back

or be miserable either! Good luck.