2)Vitamin D:- It is very useful in gaining weight. It increase the quantity of Testosterone, which helps to build muscles. Also Vitamin D absorbs calcium very well.
3)Fish Oil:- It contains plethora of fats, calories and other nutritional elements. It also contains omega 3 fatty acids which is used to synthesis muscle protein and helps to gain weight.
4)Whey Protein:- It contains all weight gaining elements like sugar and fats. It is easily digestible. It also helps to improve metabolism. It should be taken twice or thrice in a day