It won't matter, but 1000ml is too much. A catty of milk is 500ml a day. Milk is a food with high calcium content, but improper consumption will waste the calcium in it. The calcium absorbed by the body in a day is limited, and it is not appropriate to eat too much. Moreover, milk is a gas-producing food. If you have constipation, you should drink it in moderation to avoid flatulence.