About 60% of your body is water.

Throughout the day, the body constantly loses water through sweat, urine, and regular body functions, such as breathing. Getting plenty of water from food and drink every day is key to avoid dehydration.

There are various opinions as to how much water to drink in a day.

Most health experts usually recommend drinking eight 8-ounce glasses, which is equivalent to ~ 2 liters a day—this is called the 8×8 rule.

Some experts also suggest constantly drinking water throughout the day even when you’re not thirsty.

There are several internal and external factors that affect the amount of water you need; it typically varies from person to person.

Here we look at some studies related to water intake to separate fact from fiction. We also explain herein how much water to drink a day and how to stay well-hydrated.

How much water a day?

The amount of water a person needs varies. There are a lot of things that can affect your water intake needs.

According to the U.S. National Academies of Sciences, Engineering, and Medicine, adult women should drink 11.5 cups (2.7 liters) a day and 15.5 cups (3.7 liters) a day for men.

This already includes fluids from the food you eat, water, and beverages like juice and tea. The foods you eat also contribute an average of 20% of your water.

Factors affecting your water intake

How much water an individual might need depends on the following factors.

The temperature or season. Warmer months can cause you to feel thirsty due to perspiration.

Your environment. Spending more time in a heated room or outdoors in hot temperatures or under the sun might cause you to feel thirstier faster.

Location. If you live in dry, humid, or hot areas, as well as at a high altitude or in the mountains, you are more likely to need more water.

Activity level. Intense activity or exercise will cause you to lose water through sweat. If you are more active throughout the day, you will need to cover water loss by drinking more water.

Diet. Drinking caffeinated beverages, such as coffee, might cause you to lose more water through extra urination, necessitating an increased water intake. If your diet is also high in sugary, salty, or spicy foods or you don’t eat a lot of hydrating foods, like fresh fruits and vegetables, you will also need to drink more water.

Pregnancy. You need to stay hydrated if you are pregnant or nursing a baby, so you will also need to drink extra water.

Health. Drinking more water is necessary if you lose fluids through diarrhea or vomiting, if you have an infection, a fever, or health conditions like diabetes. Some medications such as diuretics can cause you to lose water.

Effects of water intake on brain function and energy levels

Many people believe that your brain function and energy levels will start to suffer if you are not staying hydrated throughout the day.

Several studies support this.

A study in healthy young women found that a 1.36% fluid loss post-exercise increased the frequency of headaches and impaired mood and concentration.

Another study in 12 men found that not drinking water for 36 hours resulted in short-term memory, fatigue, and affected attention and focus.

Even mild dehydration can adversely affect physical performance. In fact, a clinical study in men found that a 1% body water loss reduced muscle strength, endurance, and power.

Drinking water to lose weight

Many people believe that drinking more water increases your metabolism and curbs appetite, thereby resulting in weight loss.

Drinking more water than usual has been linked to a reduced body weight and body composition scores.

In addition, another study found that chronic dehydration has been associated with cardiovascular disease, cancer, diabetes, and obesity.

In another older study, researchers estimated that drinking 2 liters of water throughout the day caused a 23-calories-per-day increase in energy expenditure due to a thermogenic response, or a faster metabolism. Although incremental, the amount could add up over time.

Moreover, drinking water 30 minutes before meals may help reduce the number of calories you consume, leading to weight loss.

Another study showed that people who drank 500 mL of water before meals experienced a 44% weight loss over a period of 12 weeks.

Generally, drinking plenty of water, particularly before meals, may help you manage your appetite and maintain a healthy body weight, especially when coupled with a well-rounded diet.

What’s more, drinking adequate amounts of water may offer several other health benefits.

Does drinking plenty of water help prevent health problems?

Generally, drinking adequate amounts of water is vital for your body’s overall functions. In fact, several health conditions, such as the following, may also improve when you increase your water intake.

Urinary tract infections. Increased water intake has been shown in recent studies to help prevent recurring bladder and urinary tract infections.

Skin hydration. Some studies demonstrated that increased water intake results in better skin hydration. More research as to its effects on acne is necessary though.

Kidney stones. High fluid intake has been found in an older study to reduce the risk of kidney stones. However, further research is needed.

Constipation. An increase in water intake helps improve constipation.

Do other fluids count to your total?

Your fluid balance is composed of not only plain water but also other drinks and even foods you consume.

Being a diuretic, caffeinated drinks, like tea or coffee, are believed to not help you hydrate. However, the truth is that even caffeinated drinks can also contribute water to your body overall.

Moreover, foods, including fruits, vegetables, fish, meats, and eggs, also provide water.

Caffeinated drinks and water-containing foods can add and help maintain your fluid balance.

Ways to Increase Water

Listen to your body. Your body will know when and how much to drink. Thirst kicks in when you are thirsty.

Choose water. Go with a tall glass of water instead of energy drinks or soda.

Drink water constantly throughout the day. Make sure you constantly drink water throughout the day.

Always bring a refillable water bottle. Always keep a refillable water bottle within your reach.

Add a healthy flavor enhancer. You can add some fresh lemon, lime juice, or cucumber slices in your water to add flavor.

Signs of hydration

Maintaining your fluid balance is highly essential for survival. That is why your body knows and can control how much and when to drink. Thirst kicks in when your water content is below a certain level.

Thirst is a reliable sign of dehydration; however, it may not be enough for exercise performance of optimal health.

When thirst first kicks in, you may already experience some effects of not being well-hydrated, such as headaches or fatigue.

The color of your urine can also help you determine whether or not your fluid intake is enough. Your urine should be clear and pale.

If you are sweating, especially during hot weather or exercise, make sure to replenish the water loss with fluid.

Athletes who have done intense exercises may need to couple their water with electrolytes, such as sodium and other minerals.

Pregnant and lactating women should also increase their water intake.

If you are vomiting, have diarrhea, or experiencing fever, you should also up your water intake.

Upping your water intake may also help you achieve weight loss in no time, especially when you drink water before each meal.

As you age, your thirst mechanisms may start to malfunction, requiring older individuals to consciously watch their water intake. Adults over 65 years old have been found to be at a higher risk for dehydration.

Overhydration

Although drinking water throughout the day is recommended, too much water intake can be dangerous. It may cause water intoxication.

Overhydration happens when your electrolytes become too diluted. And if your electrolytes become dangerously low, it can be fatal—that’s very rare though.

You know you are overhydrated when you experience some symptoms of drinking too much water, such as nausea and vomiting, headache, and changes in mental state like disorientation or confusion.

If left unmanaged, overhydration can lower the levels of sodium in your blood, which can cause more severe symptoms, including spasms, cramps, or muscle weakness; seizures; unconsciousness; and even coma.

Conclusion

At the end of the day, the required water intake varies from person to person, depending on several factors, such as your diet, level of activity, and health.  No one can exactly tell how much water a person needs.

Try experimenting and see what is best for you because some people may function better with increased water intake, while others may only experience more frequent bathroom trips.

Following these simple guidelines might be of great help to you:

• Drink water more often than usual throughout the day to achieve a clear, pale urine.
• Drink when you’re thirsty.
• Make sure you compensate for the water lost from sweating, particularly during hot seasons and intense activity level.

That’s it!