Of course, you can drink protein powder when you are not exercising. Protein powder mainly increases the content of protein in the body. After a lot of exercise, the body will be in urgent need of protein, carbohydrates, creatine and so on. Eating protein powder is to quickly supplement these nutrients, so as to achieve the effect of long muscles. If you don't exercise, you may not need so much nutrition. If you drink protein powder, you may get fat instead of gaining muscle, but if you exercise four times a week, it doesn't matter.