First of all, you should have a good mood and try to make yourself happy, so as to increase your food intake and supplement the nutrition your body needs.

Then there is more exercise, which can also increase food intake, and at the same time, it can keep fit and not be bloated.

Third, don't have the bad habit of smoking. Even if you do, don't smoke within half an hour before and after meals, which will affect your appetite and be bad for digestion.

Fourth, don't be partial to food. You should supplement both vegetables and meat. Maintain a balanced nutrition. You can buy some calcium tablets and vitamins if necessary.

Fifth, good sleep habits are also essential.

Actually, I used to be very thin, with a height of 1.75m and a weight of only 52kg. In this way, I gained 5kg in less than a month, and now my weight has reached 60kg. Although I am still thin, I am already very happy.

It's just some of my methods, because everyone's physical quality is different and may have different effects on different people. I just hope it works for you.