my daughter is 1year 10 month old but she is 8.5 kg she can't gain weight her born weight is 1.8 kg please suggest me how gain his weight

A. I would like to tell you currently that if the child is not gaining weight that you need to check with your doctor to know and understand what maybe the reason behind it because if your child is eating Veena healthy diet still if the weight is not increasing and the doctors would be able to tell you the reason after examining your child