Hi . I Am 26 Years Married . My Height

Hi . I am 26 years married . My height is 166 cms and weight 60 kgs . I want gain weight . I look very weak and not like a 29 year old at all .I want to try rich foods but I don feel hungry most of the time . So i dont eat properly. I don have any other acute illness or disease. All my medical reports are good . What treatment is best . Nutrigain powder is effective ?