Water contains no calories.
It is absorbed into the body through the stomach and gut, and leaves the body as urine, sweat, and, at times, vomiting and diarrhea. Some water intake is always needed to balance the water lost by meeting normal body functions. However, losing more water through a lot of sweating or severe vomiting or diarrhea increases the body's need for water intake. The body has ways of showing when it needs more water. Thirst is the most obvious sign.