Fall in New England is HERE, it is vibrant, and it is the glorious respite we Bostonians receive as payback for the cruel, frosty months to come. Ah yes, it is the fall that solidifies our desire to live in this part of the country; before we all spend the months of December through March (often April) threatening to flee our sacred home on social media. I got to spend this past quintessential fall weekend at Mt. Washington in New Hampshire, where we walked amongst the foliage and breathed in that fresh, fall air.
While sitting around the fire, we got to talking about water. My brother-in-law then declared, in my presence no less, “That whole ‘drink 8 cups of water’ thing is a myth anyway.” He claimed he just read an article about it. Naturally, my family-in-law immediately turned their heads to me inquisitively, simply asking, “Dietitian?” Well I happen to know my brother-in-law is a smart, well-read guy, so I didn’t jump down his throat right away. I know that nutrition information is constantly changing and is a gray area AT BEST. So before I hopped up on the soap box, I had to do some research.
The article he was likely referring to was “No, You Do Not Have to Drink 8 Glasses of Water a Day”, published in The New York Times August 24, 2015. It is written by Aaron Carroll, pediatrician and professor of pediatrics at Indiana University School of Medicine. Now, my mom got her graduate degree from Indiana University, so I tried to hold back my bias and read the article from beginning to end. He made some good points. I did some additional research, which also made good points. Conflicting information is kind of a hallmark of the nutrition field, so usually it’s about taking the research and molding it to fit your individual lifestyle. So with that, here are my conclusions on this water issue:
- The Institute of Medicine sets the daily recommended intake of water as 2.7 liters (about 11 cups) for women and 3.7 liters (over 15 cups) for men per day. This is clearly more than the 8-cup-per-day rule, which was an interpretation of a 1945 Food and Nutrition Board recommendation. To further confuse you, you could calculate your individual water recommendation based on 35-40 milliliters per kilogram bodyweight per day (ex. an 150-pound person weighs 68.2kg, thus would need 2,387-2,728ml per day). So which one do you follow?
- Remember that your daily water intake includes all the food and beverages you consume in a day. Fruits and veggies are very high in water content, but even beverages like coffee and beer contain water. So you’re likely getting 8 cups of water a day even if all 8 cups aren’t coming from clear fluid.
- Your personal water recommendation will depend on your age, gender, activity level, external environment, etc. etc. The point here is there’s no one-size-fits-all, just like anything in nutrition.
- Yes, there isn’t clear clinical evidence that 8 cups of water a day, or even 15 cups, is the correct recommendation. A lot of public health campaigns make it seem like most of the population is constantly dehydrated, which isn’t necessarily the case. Some of this research is sponsored by bottled water companies anyway.
Here’s why I support the 8-cups a day recommendation, regardless of the lack of conclusive evidence around it. Water is essential for maintaining fluid balance, regulating internal temperature, and keeping our muscles hydrated. If we give people a goal to reach like 8 cups per day, they typically will drink more water than they would without a goal. Especially with kids, we want them to drink more water to hopefully replace sugar-sweetened beverages like juice and soda. It’s not necessarily about the exact AMOUNT of water we drink, it’s the fact that we’re drinking water AT ALL. Focusing on a daily water goal ideally causes us to think about choosing water over soda, and fruits and veggies over high-sodium processed foods.
Regardless of which water recommendation you choose to follow – 8 cups, 2.7 or 3.7 liters, 35-40 milliliters per kilogram – try to just drink MORE water. Keep it simple. You may not reach the goal to a T, but you’ll be more focused on hydration and choosing foods with high water content. You’ll run into information overload if you Google this, so save yourself since there isn’t a clear answer here. There just isn’t enough evidence. Create your own answer that works for your lifestyle and daily routine. Let’s put it this way: we don’t know if we need exactly 8 cups of water a day, but it certainly doesn’t hurt to drink that much.