How Much Should You Drink During Exercise?

Is there such thing as drinking too much or too little water during exercise? Should you take salt pills or electrolytes to replenish your supply?

Ben Greenfield
4-minute read
Episode #82

In the episode How Much Water Should I Drink, my fellow Quick and Dirty Tips expert Nutrition Diva busts 2 popular myths:

  • That you need to drink 8 glasses of water per day

  • That caffeinated beverages, such as coffee and tea, are dehydrating.

But what about during exercise? How much water should you drink when you’re working out? Do you need to drink water at all? And what about salt pills, sports drinks, or electrolytes? Do you need to take those too? You’ll find out the answers in this article.

The podcast version of this episode is brought to you by Betterment, an easier way to invest. Visit www.betterment.com/getfit.

Water Loss During Exercise

Water loss during exercise can be significant. To put this in proper context, I’ll tell you about a recent test I did to determine how much fluid I lost in sweat during exercise and how much salt was in that sweat.

For this test, which was overseen by a professional research team in a laboratory, I ran on a treadmill in a 95 degree room at my maximum exercise capacity for 45 minutes. I was weighed before and after the test, and even the towel I used to wipe sweat off my body was accounted for in the post-test weighing.

But that wasn’t all.

I was also required to record every morsel of food that I ate, and to collect all my urine during the 24 hour test period in a special jug. I was also hand-bathed in deionized water after the test, and that water was analyzed for sodium levels, which allowed researchers to find out exactly how much salt I was losing in my sweat. If you care to watch a video of the entire procedure, then see How Much Salt Do You Lose In Your Sweat?

Ultimately, the results revealed that I personally sweat over 2 liters of water per hour!

In a less hot climate, such as you might encounter when exercising at the gym, the average person sweats between 0.8 to 1.4 liters (about 27.4 to 47.3 ounces) per hour during exercise.

To help you visualize this amount, the average bike water bottle holds about 20-24 ounces of fluid.  In my case, I would need to consume nearly 3 full water bottles per hour to stay fully hydrated (although the highest human sweat rate recorded is 5 liters, or 169 ounces, per hour).


All content here is for informational purposes only. This content does not replace the professional judgment of your own health provider. Please consult a licensed health professional for all individual questions and issues.

About the Author

Ben Greenfield

Ben Greenfield received bachelor’s and master’s degrees from University of Idaho in sports science and exercise physiology; personal training and strength and conditioning certifications from the National Strength and Conditioning Association (NSCA); a sports nutrition certification from the International Society of Sports Nutrition (ISSN), an advanced bicycle fitting certification from Serotta. He has over 11 years’ experience in coaching professional, collegiate, and recreational athletes from all sports, and as helped hundreds of clients achieve weight loss and fitness success.