I do not know the exact numbers, but I do know - the issue is very very old - that when relief comes to famished victims of wars, the relief workers feed the famished victims very carefully and very slowly, so as to not cause MORE harm.

To me, going from 1000 kcal's to 3000 kcal's in a matter of days sounds dangerous. I realize that famished victims of armed conflicts eat much less than 1000 kcal's, but still, the point remains - you need to be careful and slow.