The talk: It's nature's sport drink

The truth: It's a fine postworkout chug for the average active Jane,

but it falls short for more hard-core athletes. The gist: When you exercise, you sweat out a lot of sodium and some potassium.

You should replace both after intense sweat sessions (more than an hour a day), so your muscles contract properly. Coconut water is a potassium powerhouse, delivering roughly 600 milligrams per cup, about 175 mg more than a banana does and 13 times what most sport drinks offer. 

"The problem is that it has only about 30 milligrams of sodium per cup; we lose much more than that during a long workout," Applegate says. Thus, serious athletes may need a sport beverage with a higher sodium-to-potassium ratio, such as Gatorade or Powerade Ion4; lighter exercisers can rehydrate with whatever they like best, including coconut water or plain H²O.