Do you usually exercise? If you don't exercise, you can only go on a diet. The staple food breakfast decreased 1/3, and the lunch decreased 1/3. If you feel hungry, you can eat an apple and drink more boiled water, so you can get used to it. As long as it lasts 1 month, it is not a problem to weigh more than 15 kg. The point here is that dinner must be served.