Four words are Discipline, Travel, Candy and Hilarity.
What I have in mind is a pill-like candy for girls to take during their travel time, which could only be taken 1 capsule a day and no other things. The candy could provide body with necessary nutrition while make people very skinny with good body shape but only during the few days. At the same time, however, people will feel extremely hungry and dizzy. If they take other things, however, they will immediately be back to their normal body shape. It’s their decisions to take the candy or not, to have wonderful pictures during travel time or not and show off to friends.