A person’s weight can transiently fluctuate with fluid shift from intake or loss. Since water has zero calories, and metabolism of water requires energy, consuming water therefore results in caloric expenditure. It takes 1Kcal to raise the temperature of 1L of water by 1 degree Celsius. This means drinking 4 cups of room temperature water roughly burns 17 Kcal. The colder the water, the more calories lost. Excessive water consumption, however, can be dangerous. Always consult your physician before beginning any weight loss program.