I am 45 yrs old with body weight 54 kgs. 1)Need to understand how will Nutrigain help in building muscles and gain weight. 2)What does it contain 3)Will it not effect digestive system and lead to constipation. 4)How much amount need to be consumed per day and which part of the day. 5)Normally how long will it take to build up. I do regular free hand and light weight exercise. 6) What is yhe cost of the powder and where do I purchase from.