This is why you should never ever compare your physical appearance to those of idols, because more than half of them are starving themselves still.
In a recent interview, Infinite members talked about their past diets including:
"In the past, we used to go on a diet without eating anything. During promotions, we survived with IV drips. There were times where we would get IV drips at night and attend schedule the next morning." Nowadays, I make sure I have two meals. When doing the choreographies, I tend to lose weight so I try to eat well, and whenever I eat with hyungs, it sincerely feels like we're a family." - Sungjong