Why you don't need 8 glasses of water a day

You know the old rule that you need to drink eight glasses of water every day? It's simply a myth, says Dr. Jen Gunter. In this episode, she explains the amazing way your kidneys keep your system in balance -- and how you can really tell if you're dehydrated.
Think you know how your body works? Think again! Dr. Jen Gunter is here to shake up everything you thought you knew -- from how much water you need to drink to how often you need to poop and everything in between. This TED original series will tell you the truth about what's *really* going on inside you.

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