Health issue. I do to gain his weight?

Your child definitely is underweight for his age. The most common cause for it is improper diet. The first thing to do is to improve his diet. This will include - Stopping all kinds of junk food like chips, maggi, cola drinks and biscuits - eat homemade roti instead of store bought bread. - focus more on home cooked meals. - increase green leafy vegetables, salads and fruits in diet. - staples like rice, roti and potatoes need to be reduced in the diet. These will just fill up the baby's stomach. They should form about 30% of the meal. The rest should be vegetables. - increase the intake of butter and ghee in the diet. - please stop breastfeeding the child in case you still continue to do so. - Reduce milk. One glass (200ml) in morning and evening each should be enough. - eggs are a great source of proteins. 2 eggs a day should help. Cook them any way you like. - if you are non-vegetarians, please eat chicken/fish at least once a week. If not, then dals or soyabean should be good. Children can be fussy eaters. So a lot of effort will be required on the family's part to improve the dietary habits of the child. It won't happen in a day. It has to be a slow process. And it has to be consistent. Try that the whole family sits together and eats. Children emulate what they see. The dietary changes have to be embraced by the family too. It means not getting any outside food into the house. It will only tempt the child more and we dont want that to happen.