First, drinking milk on an empty stomach is not conducive to the digestion and absorption of food, there is more water in the milk, more milk on an empty stomach, it will dilute the stomach acid, affecting the digestion and absorption of food.
Secondly, drinking milk on an empty stomach is likely to produce harmful substances. After drinking milk on an empty stomach, the milk protein, amino acids have not had time to fully digested and absorbed to the colon, the bacterial decomposition in the colon will produce a lot of harmful substances, affecting the health of the intestinal tract.
Third, drinking milk on an empty stomach causes a waste of nutrients. Milk is rich in protein, drinking milk on an empty stomach, these proteins are difficult to be absorbed by the body, part of the protein just as calories consumed.
So, it is not recommended to drink milk on an empty stomach, you can drink milk with other foods, such as cake, bread, steamed bread and so on. If you drink only a glass of milk on an empty stomach without eating other foods, you may be able to play only the role of milk to replenish energy. Because the body needs to supply energy, breathing, heartbeat, including body temperature need calories to maintain, and if you can not provide carbohydrates in a timely manner, the body will take the protein as carbohydrates to decompose, and then to achieve the role of energy supply.
And the purpose of drinking milk is to provide protein for the metabolism of the body's cells, but if the milk is broken down as carbohydrates, there is no better protein to supplement the cells' metabolism. When eaten with carbohydrates, milk will be able to play the appropriate role, by other foods such as bread for energy, and milk can be supplemented with protein to complete the cellular metabolism of the needs of the body, and thus play the role of milk should be.