The human body is roughly 60% water. It is also always losing water, be it through sweat, urine, or even through natural respiration. Because the body is constantly losing water over time, drinking water is a necessity to avoid dehydration. Look into the question of "how much water should you drink?" online, and you will likely find some conflicting opinions.
One of the most common answers, championed by some health professionals, is the "8 by 8 rule"--eight 8-ounce glasses a day, equating to 1.89 liters. Others believe that it is best to sip regularly throughout the day, regardless of thirstiness. When even the experts are unsure about how much water you should drink, the likeliest answer becomes "it varies with the individual." This article plans to look over the different claims in order to provide you with the information you need to make the most informed decision.
So How Much Water Do You Need Each Day?
Every person's body and health needs are unique. When it comes to adults, the baseline, according to The U.S. National Academies of Sciences, Engineering, and Medicine breaks down as follows:
- Women need a daily water intake of 11.5 cups, roughly 2.7 liters
- Men require a daily water intake of 15.5 cups, a liter more than what a woman needs.
These amounts come not just from water but also from tea, juice, and even food. Roughly 20% of your daily water intake comes from what you eat.
It is important to reiterate that these are guidelines, and there are other factors that play into the “how much water should you drink?” question. These factors include:
- Your location. Dry, hot, and/or humid environments carry a greater toll on the body's ability to keep hydrated than cooler climates. Increased water intake is also necessary for anything living at high altitudes, such as in mountainous terrain.
- Diet. Caffeinated beverages, like coffee and soda, induce urination, meaning you must drink even more water to offset the liquid lost going to the bathroom. A diet rich in salts, spices, or sugars will also contribute to a higher risk of dehydration without consuming a commensurate amount of water. Lastly, a diet bereft of hydration-rich foods, like cooked fruits and vegetables, requires an increase in how much water you need each day.
- Temperature. Warmer months demand more water than cooler ones because you sweat more.
- Environment. If most of your day is spent exposed to sunlight or in high temperatures, like a boiler room, you will need to drink more.
- Activity level. People who are active during the day or who spend a lot of time on their feet require more water than people who work a desk job. Remember to drink water during and after exercise or other strenuous activities.
- Health. Anyone struggling with an infection or fever is going to dehydrate more quickly as the body violently forces out the nastiness. Diabetics are also more prone to dehydration, as are people who rely on medications that induce urination, known as diuretics.
- Pregnant or nursing. Breast milk is derived from the mother's internal reserves of water. In short, mothers are not only eating for two but drinking for that many as well.
These are the factors that will affect how much water you should drink.
Do Water Levels Influence Energy and Brain Activity?
People say that dehydration takes a toll on our ability to function, and many studies back such claims up.
- One study discovered that losing 1.36% of body fluid after exercising resulted in problems with mood, focus, and more frequent headaches.
- Another study of 12 collegiate men discerned that going 36 hours without water had a severe negative effect on energy level, focus, reaction time, and short-term memory.
- A study on elder men in good health noted that losing even 1% of body fluid sapped away power and lasting power. While a 1% loss may seem trivial, it signified a lot of sweating or under-hydrating while spending prolonged time in a very warm room.
Does Water Intake Help Weight Loss?
One study discerned that greater water intake leads to a loss of body weight and another study drew a connection between health issues like obesity and diabetes to chronic dehydration. An older study pointed out that imbibing 2 litters in a day helped optimize metabolism to burn an extra 23 calories a day, which can add up over the years. One week of this routine would mean burning 161 additional calories, and burning 161 over the 52 weeks of a year adds up to over 8,000 extra burnt calories.
Imbibing water 30 minutes prior to a meal tends to reduce the caloric intake of the meal because the body sometimes has trouble distinguishing between hunger and thirst. Evidence suggests that people who imbibed 17 ounces before a meal lost 44% more weight over the span of three months than people who went straight to their meals. In short, properly hydrating before a big meal can help curb appetite and contribute to shedding some pounds.
Does Drinking Excess Water Help to Prevent Health Issues?
While water is needed for the body to function, maybe you are curious about whether changing how much water you should drink will keep you healthier or not. Research shows that drinking greater amounts of water helps manage constipation, kidney stones and bladder/urinary issues, and even skin hydration.
Do Other Fluids Influence Water Intake?
If you want to stay hydrated, your options are greater than just basic tap water. While caffeinated drinks are claimed to harm hydration because caffeine causes increased urination, the diuretic qualities of soda and tea are minimal, meaning that such drinks are still a valid means of staying hydrated. A lot of foods contain water to some degree: eggs, fish, fruits, meat, and especially vegetables are all suitable forms of "edible water."
In short, sticking to a diet that regularly involves tea or coffee and is paired with water-rich solids is a perfectly acceptable diet to maintain proper hydration.
Proper Hydration is Essential to Survival
The human body requires a lot of water and has entire mechanisms dedicated to regulating how you go about adding water to it. The most basic of these mechanisms is when you feel thirsty. Because thirst is just as basic a biological function as breathing, i.e., you do it without ever consciously acknowledging it, your body knows when to nudge you to go grab a drink.
While thirst is a useful gauge for letting you know when you are dehydrated, it should not be the sole indicator of being under-hydrated. By the time your body tells you that you are thirsty, you may already be grappling with the consequences of various levels of dehydration, like fatigue or headaches. The color of urine has long been used to gauge a person's health, and this extends to observing how hydrated you may be. The closer your urine is to clear and pallid, the better you are in terms of hydration.
While the 8x8 Rule exists without scientific backing, there are times when you should adjust how much water you should drink. If you happen to be sweating a lot, either from exercise or living in a hot, dry environment, you should drink more water. Consider athletes, who do long, intense exercise routines; these people know how to answer the common question, “how much water do I need each day?” They also hydrate while adding other nutrients they burn up during their exercise.
Remember to drink more water if you are nursing or pregnant, suffering from a fever, or coping with bouts of vomiting or diarrhea. If you want to lose weight, increasing how much water you should drink may also be a good solution for the long term. It is also worth reiterating that the elderly need to be more mindful of their water intake because their body's ability to sense when they are thirsty starts to misfire after the age of 65.
Wrapping Everything Up
Most people never need to answer the question “how much water should you drink?” because their bodies will let them know when they need to drink up. That said, there are conditions and situations where you may want to willfully drink more water than normal. Because no one but you can gauge how much water you should drink, feel free to play around with how much water you need each day; some people seem to work better when they drink more water than the average person, while others will complain about the increased need to visit the bathroom.
If you want a basic summary of how much water a human adult needs to function properly, abide by these guidelines.
- Drink often enough over time that your urine is pale and clear.
- Drink whenever you feel thirsty.
- When you expose yourself to an environment or activities that cause you to sweat, be sure to drink enough water so that you can offset the amount of fluid you lost through sweating.