“Drink your weight in water” and other lies.
A few years ago Heinz Valtin, a kidney specialist from Dartmouth Medical School, wanted to know if the common advice to drink eight, eight-ounce glasses of water per day could hold up to scientific scrutiny.
After scouring the peer-reviewed literature, Valtin concluded that no scientific studies support the “eight x eight” dictum (for healthy adults living in temperate climates and doing mild exercise).
In fact, he found that drinking this much or more “could be harmful, both in precipitating potentially dangerous hyponatremia and exposure to pollutants, and also in making many people feel guilty for not drinking enough. Not a single scientific report published in a peer-reviewed publication has proven the contrary.” (American Journal of Physiology—Regulatory, Integrative and Comparative Physiolog, 2002).
Dr. Margaret McCartney in the British Medical Journal discusses research which reveals how drinking when not thirsty can impair concentration, rather than boost it.