More than 70% of the earth is covered with water (1), and our bodies are comprised of up to 60% water (2). With the ubiquity of water all around and in us, it is no surprise that our bodies are highly adapted to this precious combination of hydrogen and oxygen.
Our bodies use water for a multitude of activities, which include regulating body temperature, lubricating joints, carrying nutrients and oxygen to cells, and moistening soft tissues such as in the mouth, eyes, and nose, as well as preventing constipation (3).
While conventional wisdom hearkens drinking 8 glasses of water per day, the scientific evidence of this requirement is unproven. Scientists and medical providers are unsure of where this conventional wisdom began. Some have suggested the root of this advice comes from a recommendation published in 1945 from the Food and Nutrition Board of National Research Council (4). This source suggested 2.5 liters of water daily or “1 milliliter for each calorie of food.” However, the NRC continued this suggestion with “most of this quantity is contained in prepared foods” (5). In other words, the water we consume is not only in a glass of pure water—it’s in fruits, vegetables, even coffee. It seems that this closing advice may have been ignored over the decades.
Our bodies are highly efficient at balancing our water and salt balance through the stimulation of antidiuretic hormone, which triggers the saving of water in addition to the thirst mechanism (4). In other words, simply responding to the feeling of thirst can help to ensure optimal hydration.
While a 2 percent decrease in body weight from fluid loss can lead to reductions in short term memory, efficiency in solving math problems, and other cognitive measures, dehydration can offer an advantage in certain situations (6). For instance, Haile Gebrselassie, a retired elite marathon runner, lost 10 percent (around 12 pounds!) of his body weight during some races. Although Gebrselassie’s sweat rate is not commonplace, some elite marathon runners increase their pace as they become lighter (6). While attempting this strategy to win a race is not recommended, it is worth acknowledging that it has improved some athlete’s performance.
Although there is no magic number for all bodies, water is essential for life and health. Drink water when you’re thirsty, and your body will have one of the most important tools needed to keep your brain and body at peak performance. One notable exception to this is the elderly, who often experience decreased sensitivity to the body’s natural thirst mechanism (7). That being said, it is recommended for older individuals to consistently drink smaller amounts of water throughout the day to prevent dehydration (7). All in all, this is a good idea for everyone, although younger individuals may more reliably rely on the body’s thirst mechanism as a reminder to stay hydrated.
If you want to learn more about being in tune with your body, either on your way to recovery or as part of your regular fitness routine, give us a call to set up a new patient appointment! Dr. Haggquist looks forward to guiding you on your way to greater health, using an integrative, osteopathic approach to your health.
(1) U.S. Geological Survey, U.S. Department of the Interior. (2016). How much water is there on, in, and above the Earth? Retrieved from: http://water.usgs.gov/edu/earthhowmuch.html
(2) U.S. Geological Survey, U.S. Department of the Interior. (2016). The water in you. Retrieved from: http://water.usgs.gov/edu/propertyyou.html
(3) Mayo Clinic. (2016). Functions of water in the body. Retrieved from: http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/multimedia/functions-of-water-in-the-body/img-20005799
(4) Ettensohn, K. (2001). Refuting the Aqua-Dogma: An interview with Dr. Heinz Valtin. Retrieved from: http://dujs.dartmouth.edu/wp-content/uploads/2008/04/aqua-dogma.pdf
(5) Food and Nutrition Board, National Academy of Sciences. (1945). Recommended Dietary Allowances. National Research Council, Reprint and Circular Series, No. 122, 1945 (Aug), p. 3-18.
(6) Sohn, E. (2016). Maybe you don’t really need to drink so much water every day. Retrieved from: https://www.washingtonpost.com/national/health-science/maybe-you-dont-really-need-to-drink-so-much-water-every-day/2016/11/04/9bcb32e0-9acb-11e6-b3c9-f662adaa0048_story.html#comments
(7) Morrow, K. (2015). Proper hydration in the elderly. Retrieved from: http://www.livestrong.com/article/497013-proper-hydration-in-the-elderly/