Question: how much water weight can a person lose in a day?
Answer: Water makes up 60% of your body weight, and it's one of the first things you lose. Fat mass doesn't change overnight, but you can lose as much as five pounds of water in a day. Average 24-hour urine loss ranges from 800–2,000 milliliters of fluid or about 1.8–4.4 pounds because water is heavy.