What is the right quantity of water to drink everyday? With Florence Constant

Florence Constant is a medical doctor working as global nutrition health and wellness Director at Nestlé Waters. When we asked people around the world about hydration, many talked about the quantity of water to drink every day, with a wide range of opinions. As for all our interviews, we first showed Constant a series of testimonies and we then asked her to comment and give us keys to understanding hydration's matters. The video shows a selection of her answers, and you can read her full interview below.


20QAW: What is your first reaction when you see these testimonies?

Florence Constant: When I watch these testimonies, I realise there isn’t sufficient knowledge yet about how much water you should drink, as illustrated by some of the most extreme answers, with for instance some respondents not drinking enough, while others drink too much.


20QAW: When did we start talking about “the right quantity of water to drink everyday”?

F.C.: Official recommendations for a specific quantity of water to drink everyday started in 2004, with publications in the United States, followed by similar recommendations in Europe. These are recommendations defined in relation to the age and sex of each individual. For a long time, water has been neglected with regards to recommendations, especially when compared to food and nutrition for which we’ve long had a better knowledge. So the first publications date back to 2004 with the Institute of Medicine in the United States, followed in 2010 by the EFSA (European Food Safety Authority).


20QAW: Is there a global rule?

F.C.: We’re trying to provide guidance to help the population, usually by stating figures such as 1.5L of water per day for a sedentary adult subject living in a temperate climate. This figure is based on physiological notions about how the body works, the quantity of water needed for the body to operate normally. Of course, this figure must be adapted to the age and sex of each individual, in addition to external factors such as the climate, outside temperatures, and physical exercise.


20QAW: What is the risk of not drinking enough water?

F.C.: The risk involved with not drinking enough water is firstly characterised by a dry mouth, a darker and more concentrated urine content, you also may start to feel tired, have a headache and a diminished ability to concentrate. These are some of the small signals that may alert you to a lack of water intake.


20QAW: What is the risk of drinking too much water?

F.C.: There is indeed a risk when drinking too much water, in the same way there is a risk with every type of overuse, but the main problem remains dehydration and insufficient coverage of water needs. Hyper-hydration touches a very small number of people, very rare cases, which are for the most part people who practice an intensive physical activity and don’t adequately hydrate compared to their nutrition. These are rather exceptional cases, as opposed to dehydration, which touches a much larger population and can have serious consequences when not addressed in time.


"Hydration is vital. It may be so obvious that we tend to forget about it."

Florence constant hydration


20QAW: What are the scientifically proven benefits of a good hydration?

F.C.: Hydration is vital. It may be so obvious that we tend to forget about it. We need constant, daily hydration for the body to function properly, most notably our vital organs, which are mainly made up of water, need this water intake to operate. Water is a vital element, which contributes to healthy bodily function as well as regulating the body temperature. When the body overheats, water contributes to cooling down the body, hence the importance of hydrating.


20QAW: How to encourage people to adopt healthy hydration habits?

F.C.: To encourage people to drink water more regularly, the first step is to educate them about the benefits of daily hydration, but it isn’t enough. We must also create a routine, a habit like it is the case for instance in France with the three-meal-a-day routine. In this particular case, we can implement a routine to have moments throughout the day dedicated to hydration, in the morning to start the day, then during the morning break at work, at lunch, etc.


"The human body is a wonderful machine that has an ability to adapt in order to survive."


20QAW: To what extent can the human body adapt to a certain quantity of water?

F.C.: The human body is a wonderful machine that has an ability to adapt in order to survive. If an individual is in a state of water or food deprivation, the body will try to adapt up to a certain limit. With regards to water, it can adapt up to a point, but as our body is unable to store water, you must drink water during the day, as opposed to food for which the body can draw from its reserves in case of food deprivation. In the case of physical activities and competitions such as the Olympic Games, particularly in warmer or humid climates, you usually see the athletes moving there several days ahead of time to acclimatise and adapt to the harsher climate and perform in the best possible conditions. And in this case still, hydration is absolutely essential, as they need to acclimatise to the temperature and humidity levels, which impact hydration.


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