Updated: Mar 15
"Drink 8 glasses of water a day." Where did this idea come from? In 1974 Dr. Frederick J. Stare wrote a book with Dr. Margaret McWilliams in which he stated,
“How much water each day? This is usually well regulated by various physiological mechanisms, but for the average adult, somewhere around 6 to 8 glasses per 24 hours and this can be in the form of coffee, tea, milk, soft drinks, beer, etc. Fruits and vegetables are also good sources of water.“
So, the idea that everyone needs to drink 8 glasses a day seems to have come from one sentence in a book that was really a hypothesis. But, how much water should you drink each day? It seems like a simple question but has no easy answer. Studies have produced varying recommendations over the years. But your individual water needs depend on many factors, including your health, how active you are and where you live.
Health Benefits of Drinking Water
Our bodies are made up of about 60% water and is used in the chemical processes in our bodies; it helps to keep us cool, lubricates our joints and protects the tissues that make up our bodies; it is also a major part of digestion and waste removal. Every cell in our bodies needs water to work properly. Not getting enough water can lead to dehydration — this is where you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired.
Every day you lose water through breathing, sweating, passing urine and bowel movements. For your body to function properly, you must replace this water by consuming food and drink that contain water. The National Academies of Sciences, Engineering, and Medicine have determined that an adequate daily fluid intake is:
About 3.7 litres of fluids for men
About 2.7 litres of fluids a day for women
These recommendations are for the total amount of water consumed in a day and includes water from food and any liquid that you drink, about 20% of our daily fluid intake comes from foods. However, there are some factors that need to be remembered that can mean that more water may be needed to keep you healthy.
Exercise. If you do any activity that makes you sweat, you need to drink extra water to replace the fluid lost. It is important to drink water before, during and after a workout.
Environment. Hot or humid weather can make you sweat and requires additional fluid intake. Dehydration also can occur at high altitudes.
Age. Children often don't realise that they have not had enough to drink and can become very ill very quickly. This is also a problem on hot days when kids play outside and can overheat.
Overall health. Your body loses fluids when you have a fever, are suffering from vomiting or diarrhoea. Drink more water or follow a doctor's recommendation to drink oral rehydration solutions. Other conditions that might require increased fluid intake include bladder infections as well as certain medicines needing extra water.
What About Water Being Good For The Skin?
Studies have shown that increased water intake does help to keep skin hydrated, but this is deep within the skin and can't be seen in the surface of the skin. Drinking more water is good for your overall health, but it does not make you look younger and will not make your skin glow.
Water From Foods
You don't need to rely only on what you drink to meet your fluid needs as many foods contain a surprising amount of water and have the added benefit of coming with vitamins and other nutrients. For example, many fruits and vegetables, such as watermelon and spinach, are almost 100 percent water by weight.
Examples of the water content of foods:
90% - 99% strawberries, watermelon, lettuce
80% - 89% grapes, apples, oranges
70% - 79% banana, avocado, baked potato
60% - 69% pasta, kidney beans, chickpeas (all cooked)
10% - 19% raisins, dried fruit
1% - 9% nuts, crackers, nut butters
0% oils, fats, sugars
In addition, beverages such as plant milks, juice and herbal teas are composed mostly of water. Even caffeinated drinks — such as tea and coffee — can contribute to your daily water intake. However, water is always the healthiest drink that you can have, it is sugar-free, salt-free and calorie-free.
Sports drinks, however, are not a great idea; they are sugary drinks that are made to look like a type of health product with claims of containing electrolytes. Having one every once in a while is okay, but not on a regular basis. Energy drinks are different from sports drinks. Energy drinks, generally, aren't formulated to replace electrolytes or provide any health benefits at all. They are made with huge amounts of caffeine or other stimulants, sugar, and other additives and should never be given to children or anyone under the age of 18. Some are even banned in certain countries as their health authorities feel that they are too dangerous for people to consume.
Staying safely hydrated
Studies have shown that children need between 1L - 2L of water a day, teens need roughly 1.5L - 2.5L per day and adults need between 2L and 4L. How much you need, as an individual, is not a simple thing to work out. It will depend on how much you eat, which foods you eat, how old you are, how active you are, what climate you live in, what altitude are you living at. However, the amount of water that you are consuming is probably okay if you don't often feel thirsty and your urine is colourless or light yellow. A doctor can help you to work out how much you need to drink if you think that there is a problem, but our bodies are pretty good at telling us when we need to drink more. But, to prevent dehydration and maintain good health it is best to drink water and limit the amount of sugary drinks that you have.
Drink a glass of water or other calorie-free or low-calorie beverage with each meal and between each meal.
Drink water before, during and after exercise.
Although uncommon, it's possible to drink too much water. When your kidneys can't excrete, or remove the excess water, the sodium content of your blood is diluted (hyponatremia) — which can be life-threatening. But, this isn't something that the average person needs to worry about, it takes a huge amount of water being consumed quickly to cause problems.
If you have concerns about the amount of water that you need to drink talk to your doctor. In the meantime, stay hydrated and stay healthy.