Drinking enough water can have numerous benefits. Surprisingly, it can boost the number of calories you burn. Two studies note that it can increase metabolism by 24–30% over 1–1.5 hours. This can amount to 96 additional calories burned if you drink 8.4 cups (2 liters) of. The optimal time to drink it is before meals. One study showed that downing 2.1 cups (500 ml) of water 30 minutes before each meal increased weight loss by 44%.