Quoting: FISZ
Drinking lot's of water can definitely help you lose weight. It's proven to speed up metabolism.
Drinking water before vigorous activity will hydrate the body and give it more endurance which in return will allow a person to exercise longer, thus raising the metabolism.
Quoting: Frank
no-one has EVER done a scientific study on this
Do your own study, Frank. Drink a liter of water before walking on a treadmill for 1/2 hour. The next time, don't drink anything and then walk for 1/2 hour. I guarantee you will notice a huge difference in your stamina. Excercise performed while hydrated will increase your endurance and I will stake my life on that!!!!