I don't think fitness is equal to losing fat and gaining muscle. The purpose of my fitness is to make myself live healthier, delay aging and enhance my physical function. So my fitness ideal is neither bodybuilding nor building stupid muscles, which is closer to crossfit, but not as elite and extreme as crossfit. In this framework, I said my conclusion that milk can replace protein powder, and protein powder can't replace milk. You don't have to buy or eat protein powder. Milk can completely replace protein powder, and protein drinks can be easily mixed with skim milk. For example, add some salt, potassium citrate, glucose (sugar is also acceptable), and if you exercise a lot, you can also add a few grams of glutamine. It tastes unexpectedly good. It can completely supplement what you need, protein. Protein powder cannot replace milk. Milk contains many vitamins, calcium and other nutrients. Not even in the protein powder. No matter how stupid you are, you may not be able to turn protein powder into muscle (if it is so simple, can other drugs be sold? ) Once protein is used as energy, its metabolism is very unclean, which will produce a lot of nitrogen-containing waste and increase the burden on the kidneys. Therefore, the more protein you eat, the better. Many fitness people are not stupid, and they know that eating so much protein powder can't be absorbed at all. So they combine protein powder with various supplements, and even hit human growth hormone, clenbuterol, steroids and so on. This pursuit of "beauty" of the body is admirable, but obviously, ordinary people should not. In fact, many people exercise just to lose weight and stay slim. In this regard, aerobic and dieting, supplemented by moderate strength training and flexibility and coordination training, are conducive to long-term health. Losing weight can't just rely on gaining muscle. Space is limited, so I can't share all the contents with you. In short, the answers provided by personal fitness teachers basically avoid the positive solutions perfectly.