You're a man, right? 53kg is normal. If you want to gain weight, you can not only gain weight, but also thicken muscle fibers, that is, be stronger. It's no use just eating more and sleeping more.

Make sure there is no disease in the digestive system, otherwise it is useless to eat too much;

Increase appetite, eat less crude fiber, eat more protein, moderate calories;

Intensive exercise is strength training, not just aerobic exercise;

Sleep properly, but don't sleep after eating.