Weightloss at standstill HELP!

I've been using Duromine for 11 weeks and been constantly losing excactly 2kg a week,I've lost 20kg on 10 weeks,but it seems that I'n standing still now.I keep gaining a kilo and then I battle to loose it again,but I jut can't get past 20kg.nothing has changed.I still exercise every day,even more than usual.can that be the problem?I don't care what anyone says,I know it isn't healthy,but I eat only one meal a day,that basicly consist of mostly fruit.I've been doing good for the 10 weeks,but I wonder if my body isn't starting to fight back.the last 2 weeks I've been sleeping like I'n in a coma.I'm just so tired.If there's anyone with a similar experience or a salution,please send me a msg!!would appreciate it greatly!!!