Hi.. Welcome to healthcare magic community forum..
Inability to gain weight inspite of over eating can occur due to thyroid problem (hyperthyroidism
) or due to malabsorption
conditions. Its difficult to predict which of the two is responsible without evaluation.
I suggest you to get your thyroid hormone profile checked. If they are normal, you will need gastroenterologic evaluation.
Verify your thyroid hormones and reply back for details of gastro evaluations..