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. Want to hear more? Follow Body Stuff with Dr. Jen Gunter on Apple Podcasts: https://link.chtbl.com/BodyStuffYT Visit http://TED.com/ to get our entire library of TED Talks, transcripts, translations, personalized talk recommendations and more. The TED Talks channel features the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes (or less). Look for talks on Technology, Entertainment and Design -- plus science, business, global issues, the arts and more. You're welcome to link to or embed these videos, forward them to others and share these ideas with people you know. Become a TED Member: http://ted.com/membership Follow TED on Twitter: http://twitter.com/TEDTalks Like TED on Facebook: http://facebook.com/TED Subscribe to our channel: null TED's videos may be used for non-commercial purposes under a Creative Commons License, Attribution–Non Commercial–No Derivatives (or the CC BY – NC – ND 4.0 International) and in accordance with our TED Talks Usage Policy (https://www.ted.com/about/our-organization/our-policies-terms/ted-talks-usage-policy). For more information on using TED for commercial purposes (e.g. employee learning, in a film or online course), please submit a Media Request at https://media-requests.ted.com/