Hi and thanks for the query,
changing body weight is an issue that must be considered carefully. There are issues implicated in the body weight like your genetics and diet. The genetic make up of some individuals make them to be small naturally. Eating a balanced diet could be important in ensuring an appropriate growth rate.
However, its important not to go on an unhealthy fatty diet in order to improve body weight. This could lead to major complications like cardiovascular complications, obesity in future and diabetes
. For now, I suggest you simply on a good balanced diet and be calm. A nutritionist consultation might be of help to you in achieving this goal.
Thanks and best regards,