What Happens To Your Body When You Drink 8 Glasses of Water Every Day?

Everyone knows the rule of thumb to drink 8 glasses of water a day, but what does this magic number 8 really do for your body? The body is made up of 60% water and the blood is composed of 90%, so there's no doubt that water is a vital nutrient.

Drinking enough water is critical to your health and plays a role in almost all body systems. While 8 glasses of water is a general guideline and actual water recommendations are individualized, it is an easy-to-remember number to gauge your fluid intake. A registered dietitian explains what happens to your body when you drink 8 glasses of water every day.

The Significance of 8 Glasses

It is unclear exactly where the 8 glasses of water per day guideline originated. One theory explains that it is based on 1ml of fluid per calorie of food consumed. So for an individual eating a standardized 2,000-calorie diet, that would be 2,000 milliliters of fluid or about eight 8-ounce glasses. Similar to how calorie goals differ for everyone, this general guideline may be too much water for some and not enough for others.

According to Chelsea Newbrough, RDN, "requirements may be higher or lower depending on your sex, activity levels, age, environment, and medications". Plus, plain water is not the only substance that supplies your body with hydration. You can get fluid from other sources, such as fruits and vegetables, other beverages, and even soup. Staying hydrated is extremely important so it is necessary to follow your thirst and find your individual fluid needs.

Benefits of Drinking 8 Glasses of Water Every Day

There are many benefits to drinking enough water and dehydration can contribute to fatigue, headache, and impaired mood. According to Jennifer Fiske, MS, RDN, LD, "I recommend half an adult's body weight in ounces as the minimum total fluid intake per day. Most of the beverages consumed to meet this goal should be non-caloric, ideally water". Staying adequately hydrated keeps all body systems functioning optimally including enhancing physical performance, keeping skin hydrated, and maintaining regular dehydration. Here's more on these benefits.

Maintains Fluid Balance

You can think about water as a nutrient that your body needs that is present in both liquids and foods. Fluid is lost every day through skin evaporation, breathing, urine, and sweat, so these losses need to be replaced. When your fluid intake does not equal your output, you can become dehydrated. Drinking enough water throughout the day helps to maintain this balance of input and output.

When your body needs more fluids, it triggers the thirst mechanism in the brain to give you the cue to drink. As we age, our sense of thirst does diminish, so dehydration is common in the elderly population. Certain medications can also interfere with this mechanism so it is important to be mindful of your fluid intake.

May Enhance Physical Performance

Hydration is imperative to exercise, as it plays an important role in performance, injury prevention, and recovery. Muscle cells that don't receive enough fluid and electrolytes can result in muscle fatigue and cramping. Research shows that dehydration during physical activity can have a negative effect on strength and power. It is also important to consider drinking early and often throughout a workout to replace fluid lost through sweating.

Keeps Skin Hydrated

Your skin is made up of a large proportion of water so you can bet that water intake is key to affecting how your skin looks and feels. Skin also functions as a protective barrier against excess fluid loss. While adequate hydration is important for skin health, drinking excess water won't erase any blemishes or wrinkles. But drinking enough water will make your skin look healthier and less dry.

Maintains Healthy Kidney Function

As your body's waste filtration system, the kidneys do an excellent job of transporting waste products in and out of cells. Adequate hydration makes this system work smoothly and efficiently. When you are drinking enough fluids, your urine is light in color and flows without any problems. If you are chronically dehydrated, your urine is likely darker in color and more concentrated because your kidneys need to trap the extra fluid for bodily functions. Over time, this can put you at risk for complications, such as kidney stones.

Decreases Risk of Constipation

Adequate hydration prevents constipation. When you are dehydrated, the colon takes water from your digestive tract to maintain hydration, resulting in constipation. Many people know that increasing fiber helps relieve constipation, but increasing water intake at the same time will be more effective. The fluid helps the fiber bulk up stool to keep your bowel functioning properly.

Risks and Considerations

While drinking water and staying adequately hydrated is necessary to all bodily functions, certain populations may need to be more conscious about drinking more or less depending on their needs. If you have congestive heart failure or a kidney condition, your doctor may recommend you limit your water intake. Alternatively, if you are taking certain medications, are pregnant or breastfeeding, or have a high level of physical activity, you may need to drink more than 8 glasses of water a day.

An important consideration is your fluid intake if you are an athlete. When we sweat, we are losing both water and electrolytes and the body needs a balance of both. "A sports drink with electrolytes may be more appropriate to incorporate into daily fluid intake for athletes, those that live in hot climates, or anyone with a high level of activity. Too much water can actually lead to a condition known as hyponatremia, where the level of sodium in the blood drops critically low and can lead to death", says Newbrough.

Tailoring the 8 Glasses of Water Goal

While 8 glasses of water a day is a good goal to shoot for and a helpful guideline, you may want to tailor your exact fluid intake to your individual needs. Speak with a healthcare provider or a registered dietitian to help you with this. To estimate your fluid needs, consider your urine color as well as your typical sweat loss. Additionally, consider your physical activity level, the intensity of perspiration, body size, gender, duration of physical activity, climate, and elevation. Also, speak with your healthcare provider if you have any medical conditions in which you may need to adjust your fluid intake.

Strategies for Incorporating 8 Glasses of Water Into Your Lifestyle

Getting adequate fluids is a healthy habit that everyone can get behind. Newbrough says, "Some strategies that I like to share with my clients are to carry a water bottle with them wherever they go as a reminder to take sips throughout the day. For those who struggle with plain water, you can play around by infusing it with any mix of fruits, veggies, or herbs to make it more exciting. My personal favorite is a refreshing mix of watermelon and mint".

Other strategies include buying a water bottle that is fun and makes you want to drink, using a water bottle that marks milestones you hit throughout the day, and increasing your intake of hydrating foods, such as fruits, vegetables, yogurt, and eggs. "For reusable water bottles, I customize the number of refills per day to the person's unique needs. If someone works in an environment with set break times for food and beverage consumption, I customize their water intake to their schedule and focus on opportunities before and after work," Fiske says.

While there is no "one size fits all" approach to hydration, drinking 8 glasses of water a day certainly has health benefits. These include improved fluid balance, enhanced exercise performance, healthier skin, and regular bowel movements. Speak with a healthcare provider for individualized fluid recommendations and if you have a medical condition that would limit your fluid intake.