Hello Siva.. I have gone through your post in which you have asked about Nutrigain. Nutrigain is a product made of certain herbs which are helpful for gaining weight. But these products are only dietary supplements & should not compromise on routine healthy food such as: 1. Consume more of natural diet like fresh fruits, green vegetables, milk, eggs, wheat, etc. 2. Avoid oily and junk food. 3. Stay away from smoking & alcohol. 4. Best is to stay active, exercise regularly, avoid stress, get good sleep, think positive and stay happy. And as you have mentioned about the past history of chicken pox & presence of kidney stone in both the kidneys, it will always be better to consult your treating physician before taking anything. Wish you a healthy life. Take care.