How much water should I drink? We asked five experts


Eight seems a lot …

Should I drink eight glasses of water a day?

Everyone knows that humans need water and that we cannot survive without it. We’ve all heard that we should aim for eight glasses, or two liters of water a day.

This goal seems pretty steep when you think about how much water it actually represents, and don’t we also get water from the food we eat?

We asked five medical and sports science experts if we really needed to drink eight glasses of water a day.

The five experts said no

Five X checkboxes

Here are their detailed responses:

Karen Dwyer – Nephrologist

It is enough to drink to be thirsty. The best indicator of your hydration level is the color of your urine. You should aim for a light yellow color; if very dark, you are dehydrated and need more water; if it’s clear (like water), you don’t need that much water. Excessive water consumption can be dangerous, especially in people with heart problems. The kidney has a remarkable ability to concentrate water, so if you are ‘dry’ the kidney will concentrate urine and send a message to the brain to drink more.

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Vincent Ho – Gastroenterologist

No, you don’t need to drink eight glasses of water a day. It appears that the origin of the recommendation to drink eight glasses of water per day may have come from a publication by the National Academy of Sciences Food and Nutrition Board in 1945 stating “An appropriate amount of water for adults is 2.5 liters per day in most cases. The recommendation also stated that “most of this amount is contained in prepared foods,” a fact that is often overlooked. We get a large portion of our water intake from the foods we eat. flower and eggplant for example contain 92% water. A single approach is unlikely to be helpful. Healthy adults may not need to drink an additional eight glasses of water a day. On the other hand, people with certain illnesses or living in very hot climates may need larger amounts of fluids.

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Michael Tam – GP

Eight glasses, or a little less than two liters of water, is very roughly the basic water required by a healthy fasting adult per day, who does nothing at all (for example, stay in hospital ), without particular losses (such as vomiting or diarrhea). In everyday life, we usually have additional discharge (exercise or sweating on a hot day) and we receive water from other sources. There are those that are evident in our diet, like juicy and moist foods and drinks, like fruits and vegetables. Water from food metabolism is less obvious. The conversion of fats, carbohydrates and proteins into energy in our body produces water. Rather than focusing on the number of drinks, just drink fluids when you are thirsty. Aiming for more water (especially in place of sugary drinks) is often a good idea to improve health.

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Jon Bartlett – Sports Scientist

The daily water requirements of a person are very individual and depend on a number of internal and external factors. While eight glasses of water a day is recommended as a basic requirement to meet daily physiological needs, the actual volume of water required in a day depends on daily activities, health, and the climate in which they reside. Research shows that even a slight level of dehydration can negatively affect mental and physical performance. This is further accentuated for individuals who are very active and who live in hot environments. A simple and easy reminder to make sure you are drinking enough is to drink when thirsty, and on days when activity levels are higher than normal or in warmer environments to increase consumption regularity and volume. total.

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Toby Mundel – Exercise Scientist

There are many factors that will determine how much water (from all foods and fluids, not just water!) Your body needs. These include height and body composition (weight, muscle and fat), how much you are sweating (physically active, hot or humid environment, too much clothing) or urinating (taking certain medications, being at high altitude), your health. (having fever, vomiting or illness) or condition (pregnant, breastfeeding) and diet (foods rich in water, carbohydrates). For most healthy adults, a rare sensation of thirst and light yellow (or colorless) urine usually confirms adequate water intake. Other helpful tips include drinking a glass of low-calorie fluid before and with every meal (to distinguish hunger from thirst) and drinking low-calorie fluid before, during, and after physical activity (especially if you are sweating). While rare, drinking too much fluid can also have negative health consequences, so more isn’t necessarily better.

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Written by Alexandra Hansen, Associate Editor and Chief of Staff, The Conversation.


  • Jon Bartlett – Sports Science Fellow, Victoria University
  • Karen Dwyer – Assistant Director, Faculty of Medicine, Deakin University
  • Michael Tam – Specialist GP and Joint Lecturer, UNSW
  • Toby Mündel – Associate Professor, School of Sport, Exercise and Nutrition, Massey University
  • Vincent Ho – Senior Lecturer and Clinical Academic Gastroenterologist, Western Sydney University

This article first appeared in The Conversation.The conversation


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