Drink plenty of water: don't wait until your mouth is dry.
Not picky about food.
Do more exercise.
-These are for regulating your own digestive function.
Make sure the house is clean: don't be too wet and dusty (dust is the worst for people's health).
Your eating habits and daily life should be regular.
-These are external conditions.
There is also about calcium supplementation, which is eaten by small basin friends and has something to do with fattening rice. Just take some multivitamins. It's on the sign.
In short, you adjust yourself to be healthy, and your weight gain is absolute. Keep a good attitude ~!