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- You've probably heard the advice to drink eight glasses of water a day. That's easy to remember, and it's a reasonable goal. Most healthy people can stay hydrated by drinking water and other fluids whenever they feel thirsty. For some people, fewer than eight glasses a day might be enough. But other people might need more.
www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256
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Is 8 glasses of water a day too much?
How many glasses of water do you need a day?
Is there a myth about drinking 8 glasses of water a day?
How much water should you drink a day?
Oct 12, 2022 · You've probably heard the advice to drink eight glasses of water a day. That's easy to remember, and it's a reasonable goal. Most healthy people can stay hydrated by drinking water and other fluids whenever they feel thirsty. For some people, fewer than eight glasses a day might be enough.
- Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its w...
- You've probably heard the advice, "Drink eight 8-ounce glasses of water a day." That's easy to remember, and it's a reasonable goal.Most healthy pe...
- You might need to modify your total fluid intake based on several factors: 1. Exercise. If you do any activity that makes you sweat, you need to dr...
- You don't need to rely only on what you drink to meet your fluid needs. What you eat also provides a significant portion. For example, many fruits...
- Overview
- Evidence for drinking 8 glasses of water each day
- Foods and beverages other than water can contribute to hydration
- Drinking enough water has some health benefits
- How much water should you drink each day?
- The bottom line
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Eight glasses a day may not actually be based on science. This varies for everyone, and you can get needed fluids from other foods and beverages, too.
You’ve probably heard that you need to drink eight 8-ounce (240-ml) glasses of water each day. That’s half a gallon of water (about 2 liters).
This claim has become widely accepted as fact, and it’s very easy to remember. But is there truth to this advice, or is it just a myth?
This article reviews the evidence behind the “eight glasses a day” rule and how much water we need each day.
It’s hard to pinpoint exactly where and when the “eight glasses per day” rule originated. There are theories that it may be based on a fluid intake of 1 ml per calorie of food consumed.
For someone eating a diet of 2,000 calories per day, this adds up to 2,000 ml (roughly 64 ounces), or eight 8-ounce glasses.
However, a growing body of research suggests that this broad recommendation may actually be too much water for some people and not enough for others.
While there are certainly circumstances in which water needs increase, healthy people generally don’t need to be consuming water in such large quantities.
On the other hand, not drinking enough water can cause mild dehydration, defined as the loss of 1–2% of body weight due to fluid loss. In this state, you may experience fatigue, headache, and impaired mood (1).
But in order to stay hydrated and avoid mild dehydration, you don’t need to rigorously follow the eight glasses rule — simply follow your thirst.
It’s not just plain water that supplies your body with water. Other beverages, like milk and fruit juice, count as well.
Contrary to popular belief, caffeinated beverages and mild alcoholic drinks such as beer may also contribute to fluid intake, at least when they’re consumed in moderation (2, 3, 4).
Many of the foods you eat also contain significant amounts of water.
How much water you get from food depends on the amount of water-rich foods you eat. Fruits and vegetables are particularly rich in water, and foods like meat, fish, and eggs also have a relatively high water content.
For example, watermelon is 91% water, and eggs are 76% water (5, 6).
Lastly, small amounts of water are produced within your body when you metabolize nutrients. This is referred to as metabolic water (7).
You need to drink enough water to stay optimally hydrated. Generally speaking, that means replacing the water you lose through breath, sweat, urine, and feces.
Drinking enough water may offer health benefits, including:
•Weight loss. Drinking enough water may help you burn more calories, reducing appetite if consumed before a meal and lowering the risk of long-term weight gain (8).
•Better physical performance. Modest dehydration may impair physical performance. Losing only 2% of your body’s water content during exercise may increase fatigue and reduce motivation (9).
•Reduced severity of headaches. For those prone to headaches, drinking additional water may reduce the intensity and duration of episodes. In dehydrated people, water may help relieve headache symptoms (10, 11).
•Constipation relief and prevention. In people who are dehydrated, drinking enough water may help prevent and relieve constipation. However, more research on this possible effect is needed (12).
There is no single answer to this question.
However, the National Institute of Medicine has set an Adequate Intake (AI) level for total water and total beverages. The AI refers to a level that is assumed to meet the needs of most people.
The AI for total water (including water from food, beverages, and metabolism) and total beverages (including water and all other drinks) is (15):
While this may certainly be used as a guideline, there are a number of factors, both inside your body and in your environment, that influence your need for water.
Body size, composition, and activity level vary greatly from person to person. If you’re an athlete, live in a hot climate, or are currently breastfeeding, your water requirements increase (16).
Taking all this into account, it’s clear that water needs are highly individual.
Although eight glasses of water per day is commonly touted as a science-based fluid recommendation, there’s actually little evidence to support this claim.
Water needs are highly individualized, and you can get fluids from water, other beverages, and foods, as well as from nutrient metabolism.
The 8×8 rule is not based on science and may not suit everyone. Learn how much water you need, where to get it, and why it matters for your health.
Dec 7, 2022 · You've probably heard that drinking eight glasses of water per day is key or that you should get more fluids when sick. But just how much water does a person really need?
Mar 15, 2024 · Drinking eight glasses of water a day – or about two litres – is actually more than our bodies need to stay hydrated, according to the latest research. Instead, you should drink between 1.5...
Jun 4, 2009 · You Must Drink 8 Glasses of Water Daily. Do healthy people really need liquids even when they are not thirsty? By Karen Bellenir. Health. Virtually every health-conscious person can quote...
Aug 8, 2023 · Learn how to stay hydrated in different weather, activity, and health conditions. Find out if you need 8 glasses of water a day, how caffeine affects hydration, and when to use sports drinks.
Sep 22, 2022 · Do you really need to drink eight glasses of water a day? Can drinking water help you lose weight? Does coffee dehydrate you? Experts explain the science of hydration.
