I know 4getmenot, you is a laydeee.
My point really, is that it is a mindset and no amount of gifts and denial (you�re not fat etc) /encouragement from someone else can really change that. Believe me, I tried. It might work for a week, but then next month you will find yourself at the blunt end of another �trauma�. If you are willing to invest some real time and effort, and she needs support and encouragement as she lacks her own willpower, then as suggested before, perhaps you could arrange one evening a week where you do something mildly energetic together (swimming/or an exercise class/or even AmDram! etc). The aim is that you help her get into a rhythm and potentially start to feel better about herself to the point where she sees results and has the willpower to go it alone. Organise a once every month/two months treat, such as shopping for an occasion where you both go out and live it up. If you are both in a circle of friends, the others could help out as well by taking in turns to do something energetic and with some reward at the end so that it is not all your own time taken up.