Weight gainers is a type of protein powder. It contains high amount of calories and protein as well as being low in sugars and fat. Weight gainers can effectively replace a meal. It can be used in addition to your diet to add clean calories to your bulking diet.
The actual amount of calories per serving and even servings sizes vary wildly from one manufacturer to another. Some products contain less than 400 kcal per serving while others can have as much as 1250 kcal per serving, so it’s always a good idea to read the label before you buy.
A few things to check before you buy your first (next?) bag of weight gainer: if you are lactose intolerant, you might want to go for the vegan varieties, they are least likely to contain lactose, although as mentioned before, always read the label before you buy. It is also beneficial to check what other supplements have been included in the mix, apart from oats and protein.