If it is really hard for you to gain weight but you are eager to gain weight, then don't drink skim milk! Those are for people who lose weight. 16 oz whole milk provides 16 g protein and 16 g fat. Compared with other foods, the fat in milk is generally short chain. Short-chain fats promote synthesis and prevent muscle decomposition. Compared with other fats, they are less likely to be stored as body fat. The fat in milk can help the body absorb vitamin D and reduce the risk of cancer. It is no accident that Arnold and Frank, the great men in the 1960s and 1970s, drank so much whole milk.
It is best to drink it after 30 minutes of exercise to accelerate nutrient absorption and muscle growth.