If you don't eat carbohydrates, when your sugar reserves are low, your body will get carbohydrates through other channels. One way is to convert fat into carbohydrates. In the process of fat metabolism, a very small amount can be converted into glucose, generally between 5%- 10%, and other parts can only be directly supplied with energy and cannot be converted. This is because the human body lacks enzymes to convert fat into glucose, so it is extremely difficult to convert it. On the contrary, carbohydrates can be converted into fat in large quantities.
This little fat-converted carbohydrate obviously can't meet the needs of the human body. When you don't eat carbohydrates and lack a lot of carbohydrates, protein in human muscles will be decomposed into amino acids, which will be denitrified in the liver and converted into glucose.
This practice is very wasteful. Instead of cheap carbohydrates, we eat expensive protein. As a result, because of the lack of carbohydrates in the body, most of the protein eaten is converted into carbohydrates in the body. For example, this behavior is equivalent to burning a fire to keep warm in winter. If you don't pick up branches in the Woods in front of your house, you have to go to the market to buy mahogany furniture, but you can't burn it directly after buying it. Cutting it into firewood is a very wasteful act. Think about how much is a catty of rice and beef.
So although the human body can't convert carbohydrates into amino acids (herbivores can, cows have four stomachs, and its first stomach can synthesize amino acids from cellulose in grass and free nitrogen in food), carbohydrates can protect protein. If you don't eat enough carbohydrates, most of the protein you eat will be converted into carbohydrates in your body.
So if you search for any brand of protein powder on Tmall, as long as it is 75% protein powder from protein, its instructions are all mixed with glucose or sports drinks. It is for this reason that the intake of protein together with carbohydrates can maximize the utilization rate of protein, prevent expensive protein from being converted into carbohydrates and avoid waste.
50% protein powder can be drunk directly without glucose because it contains about 48% sugar.