Monday, March 18, 2013

Hydration Nation: The 8 Cups of Water a Day Myth

Most people have heard that they need to drink 8 cups of water every day to be healthy. And water is crucial to helping our bodies work right – so it’s not surprising that water is responsible for 60% of our body weight.  But do you really need to guzzle at least 8 cups a day? Our bodies lose water every day through the kidneys in the urine, from the lungs when we breathe, and through sweating. The typical person does lose about 8 to 12 cups of water a day through these routes but, as it turns out, there are many ways you can replace that loss.
Restoring Water:
Ø  Milk & Juice: When you drink milk or juice not only are you getting vitamins, minerals, and in the case of milk, protein, you’re also replacing water loss. Both milk and juice are over 80% water so they can really make a dent in body water needs.
Ø  Coffee & Tea. These two always surprise people because many people are led to believe that the caffeine in caffeinated beverages makes them lose all the water in the beverage & then some causing an overall water deficit. Not so! Yes, it is true that caffeinated beverages are not as good as non-caf in helping you hydrate but you still get some hydration effect. In other words, you urinate a little more with caffeinated beverages but remember, you're getting a lot of water in that coffee, tea, or soda and you retain over 50% of it. Researchers have also shown that most people adjust to the caffeine level in their drinks so over time, so the caffeine does not have as much of an effect on your body. After about 3 to 5 days of drinking caffeinated beverages, the body adjusts and there is no additional loss of urine when compared to decaffeinated beverages.  
Ø  Soda.  Even soda can help you rehydrate – it’s mostly water. Your best bet is diet sodas so that you’re not adding in empty calories.
Ø  Fruits & vegetables. Fruit & vegetables contain a lot of water. Strawberries, watermelon, lettuce, cabbage, celery, spinach, & broccoli are particularly high at over 90% water. The water content of most other fruits & vegetables is over 80% so they are also good sources. For many people, fruits & vegetables can contribute 1/3 or more of their daily water needs!
Ø  Other foods. All foods contain some water, but notable water contributors include yogurt, cottage & ricotta cheeses, fish, chicken, and pasta.
Ø  Water: Water is the best hydrator – it empties from the stomach quickly and makes its way to the large intestine where it can be absorbed quicker than the other fluids.
Ø  Thirsty? Thirst is actually a pretty good guide to whether or not you need more fluids – except in older people.
Ø  Check Your Urine. The best way to tell if you are getting enough fluids is to check your urine. If you are well-hydrated, your urine will be very pale. If you need fluids, the urine is dark yellow and low in amount.
While drinking water is still a good idea, you don’t have to feel like you’re drowning in it or lug a massive, back-breaking water jug around all day long.  All beverages (except alcohol) count toward your total 8 to 12 cups and eating a lot of fruits and vegetables will also help keep you hydrated.
Can you get too much water? Surprisingly, yes! People who chug water excessively can actually dilute out their blood sodium levels to a dangerously low level. The fancy name for this is hyponatremia. Some of the symptoms can mimic dehydration – muscle weakness, muscle cramps, confusion, and decreased consciousness. It can result in death!
Beth Kitchin PhD RDN
Assistant Professor, Nutrition Sciences
University of Alabama at Birmingham


  1. Even if you're hydrating through other sources, isn't it still better to get 8 cups of unadulterated water to, for lack of better words, flush your system?

  2. Hi Lindsey - I would definitely give water the edge as the best drink for hydration because it empties from the small intestine quickly into the large intestine where it can be absorbed. So if you like drinking water, then yes, that is the best choice. But for those of us (and I am in this group) who just aren't very motivated by plain water, other fluids are still good options!

  3. I am not a big fan of water, probably because of the tastelessness (reminds me of water chestnuts and they are so useless--gaaaaaaah) or taste that's not supposed to be there. I've splashed MiO, a flavor enhancer. into my water bottles lately. Is that okay?

    Also, what are your thoughts on adding lemon or apple cider vinegar to water?