Old Rule: Drink eight glasses of water a day.
New Rule: Eat your water.
The recommendation to chug all that H2O was likely based on guidelines published in 1945. However, says Howard Murad, MD, author of The Water Secret, much of your daily requirement is contained in foods: Fruits, vegetables, beans, and cooked whole grains like oatmeal and quinoa (which soak up moisture in the pot) all deliver servings of water. And, as Murad points out, they offer the added bonus of nutrients: "Watermelon and cucumber are more than 90 percent water, but they also contain antioxidants. With a glass of water, all you get is water." You'll know you're hydrated when your urine is colorless or pale yellow and you're rarely thirsty.