We’ve all heard the recommendation to drink eight eight-ounce glasses (64 ounces in total) of water each day. But is this correct, or a just a commonly followed myth? Let’s look at why staying hydrated is so important in the first place. Then, we’ll investigate current fluid intake recommendations and the variables that can help determine the right amount for you. Plus, we’ll share tips for getting your fair share of fluids and staying healthily hydrated. So grab a glass—or your favorite BlenderBottle® shaker—fill up with your favorite beverage, and read on.
Why Water Matters
Literally every system in our bodies utilizes water, which accounts for roughly 60 percent of total body weight. Water works to flush toxins from our bodies and transport nutrients to our cells. A lack of water, or dehydration, can have dangerous consequences. A review of Water, Hydration and Health by the National Institutes of Health points to several potential health concerns related to dehydration. These include impaired cognitive, gastrointestinal, kidney, and heart function. Dehydration is commonly associated with headaches, and hydration levels may impact numerous chronic diseases.
In regards to athletics, even mild dehydration can negatively impact physical performance, with athletes participating in high-intensity or endurance activities (think tennis or triathlon) being especially susceptible. Dehydration during exercise can manifest as increased fatigue, increased perceived exertion, decreased endurance, and lagging motivation.
Fluid intake is obviously important. But how much water should you really drink?
What’s The Right Amount?
The standard “8 x 8” recommendation is right up there with digging into a daily apple to keep the doctor away. Sure, it sounds like a great common sense concept. But is 64 ounces of water an accurate and appropriate target? The answer isn’t exactly a simple yes or no—nor is it the same for everyone.
The most recent and widely accepted water consumption guidelines come from the National Academy of Science. In the NAS report on dietary intake, the official recommendation for water consumption is to drink enough to satisfy your thirst. Normally, says the NAS, most adults living in a temperate climate will naturally consume enough fluids through drinking to thirst (in addition to the water content consumed from their food) to maintain proper hydration.
NAS does, however, offer Adequate Intake (AI) dietary guidelines, and that’s where we find the most recent fluid intake goals. According to the NAS, a general guideline for adults ages 19 and older is for men to consume 125 ounces of total fluids per day (3.7 liters), while women should aim for 91 ounces (2.7 liters). It’s important to note that these numbers account for total fluid intake, including that from all beverages and food. Approximately 20% of our fluid consumption comes from our food, so the adjusted beverage guidelines are 101 ounces (3 liters) for men and 74 ounces (2.2 liters) for women.
Notably, both these AI guideline numbers are above the long-held 64-ounce threshold. But before you latch onto your new water goal, keep in mind that numerous variables influence fluid consumption needs, and it’s possible you’ll want to drink even more. These variables include:
- If you live in a hot climate, you’ll require more fluids. Likewise, hydration needs increase at high altitude, and in indoor environments with dry heated air.
- Certain common health conditions—such as fever, vomiting, and diarrhea—contribute to fluid loss, and thus require additional intake.
- Pregnant and breast-feeding women. Women need extra fluids to stay hydrated while pregnant and breast-feeding. The NAS bumps the AI guideline for total beverage consumption up to 78 ounces for pregnant women and 105 ounces when breast-feeding.
- If you exercise hard enough to sweat, you need to add extra fluids to your regimen (the amount depends on how long and hard you exercise and how much you sweat). Note: Drinking too much plain water can also pose a potential risk, particularly to endurance athletes. A condition called hyponatremia, which can range from mild to life threatening, can result when blood sodium levels fall dangerously low. Therefore it’s critical for endurance athletes to rehydrate with electrolyte replacement sports drinks, rather than water alone.
Take stock of your personal situation, and adjust your drinking habits as needed. When in doubt as to what’s best for your body, your environment, your individual health, and your lifestyle, consult a registered dietician or your physician.
Ways To Increase Your Fluid Intake
If your current fluid consumption is a far cry from the AI guidelines and you’d like to increase your fluid intake, here are a handful of ideas that may help:
- When thirsty, drink. The thirst sensation is your body’s trigger to tell you what it needs.
- Keep a refillable bottle on hand. You can make tracking your intake easier if you think in terms of “bottles” instead of ounces. For example, if you’re using a 28-oz. BlenderBottle® shaker, aim for roughly 3 ½ fill-ups per day if you’re a man; 2 ½ fill-ups if you’re a woman.
- Spruce up plain water with an infusion of fresh fruit or cucumber slices. Or opt for sparkling water (make it at home with a carbonating system such as Sodastream).
- Fruit juice mixed with sparkling water is a delicious and nutritious alternative to plain water, while cutting the high sugar content of pure juice.
- Fill your plate with high water content fruits and vegetables. Top choices include watermelon, strawberries, grapefruit, cantaloupe, pineapple, cucumber, lettuce, spinach, celery, and tomatoes.
- Free apps like Daily Water and Waterlogged help you stay on top of your hydration goals.
Then, of course, there’s the age-old way of knowing whether or not you’re properly hydrated: take a look at your urine. It should be clear or light yellow in color. If it’s dark yellow, drink up.
How do you stay on top of your hydration? Share your tips in the comments below.