I m 20 year nd my weight is 47. how to increase body nd weight.pls suggest doctor.?

Nutritionist: 47kg weight would indicate a slight frame (i'm assuming you don't mean 47 lbs.) you should be able to gain weight with a protein rich balanced diet and an exercise regimen aimed at adding muscle to your frame. I suggest you seek a primary doctor, who first assess you, and can direct you to a trained nutritionist to help you if appropriate.