My age is 17 and weight is 45.my body is weak.how can i increase my weight.suggest me diet for and also tell how to to good loocking.

If no illness, eat..: To gain weight you have to consume more calories than you are burning. Do this in a healthy way. Don't choose junk or fast food. Keep a well balanced diet and make sure you are getting all the nutrients you need. Don't cut out exercise as it is very good for the body and mind. Weight lifting and other muscle building exercises can help increase one's body mass. Do pull-ups, push-ups, sit-ups, etc.