How much water should I drink?

How much water should I drink

I think I usually drink more water than people (at least the people I know) in average do.I grew up thinking that you should drink as much as possible – almost like the more you drink the better. I think that’s what it was like in the 90’s when I was a teenager: Everyone had a bottle of water with them wherever they went, it was the cool thing to do.

But I’ve lately read about different types of reports too. Reports and studies that suggest we should not be drinking so much water and that drinking too much has actually negative effects on our bodies. That we should only drink when we are thirsty.

But how do we know how much is too much water? Haven’t we always been told that if we’re thirsty, we’re already dehydrated?

What do we need water for?

We’ve all seen the adverts that tell us to drink 8 or even 10 glasses of water a day and how drinking lots of water improves your overall health. But what is this based on? What does water do to us?

We cannot survive more than a week without water. 60 % of our body weight consists of water. Our bodies need it to:

  • prevent dehydration
  • maintain our body temperature
  • clean our system of bacteria and toxins
  • carry nutrients to our cells
  • moisten our tissues for example in our eyes and nose.

I’ve noticed that whenever I have a long meeting at work it really helps to have some water with me – it helps me to keep focused during the meeting. And while exercising having some water seems to bring instant energy. This is no surprise really as even mild hydration can make us feel tired and as if we lack energy.

Studies on how much water we should drink

The doctors of Harvard Medical School published new recommendations in the summer about how much water we should drink and they say that instead of the commonly suggested 8 classes we only need to drink 4 – 6 eight-ounce glasses of water a day. That’s just 1 – 1,5 liters a day. In addition to this we also eat a lot of water when we have fresh fruits and vegetables. We get about 20 % of our daily water intake from food.

The Institute of Medicine on the other hand suggests that we should have 2 – 3 liters of total beverages a day:

  • 13 cups (3 liters) for men
  • 9 cups (2,2 liters) for women.

According to the Institute of Medicine all beverages, not just water, count towards these recommendations.

These two recommendations do not necessarily rule out each other as we do not know whether Harvard Medical School has taken all beverages that we consume during the day into account in their suggestion.

When do you need to drink more than that?

You might need more water than that when you’re pregnant, breastfeeding or exercising.

The Institute of Medicine suggests that when you’re pregnant you should drink 10 cups (2,3 liters) and while breastfeeding 13 cups (3 liters ) of total beverages a day.

However, it seems that the danger of drinking too much water is just as serious as drinking too little. If not even more so as you can actually die from drinking too much water. Drinking too much water happens usually when people are exercising. We are obviously talking about a lot of water, but the danger is real:

There is a case where a young football player died after consuming 8 liters of fluid in 5 hours while he was exercising. And there are several similar cases among young athletes that are encouraged to drink a lot of water.

Eight liters of fluid is obviously a lot, but I think I’ve managed to drink about half of that in the same amount of time (without trying) so it’s not impossible – especially if you’re a young ambitious athlete who thinks that the more water you drink the better results you’ll get!

What happens is our kidneys won’t be able to process all the water and the sodium in our bodies can’t keep up with it. This is called (exercise-associated) hyponatremia. It’s symptoms include:

  • headache
  • nausea and vomiting
  • blurred vision
  • confusion
  • cramps

and when serious it can lead to coma or death.

The main message from the studies seems to be:

When it comes to sports and exercise we should drink according to thirst. If you sweat a lot you should consider drinking something with sodium as you lose some through sweat. The amount of water you need depends on how much you sweat, how long you exercise and how intense your exercise is. Around 2 cups (0,5 liters) seems sufficient for a 60 minute exercise class for example.

Do you find it difficult to drink enough?

I love the taste of water but I know there are a lot of people that don’t. If you’re one of them you could try sparkling water or different types of fruit infused waters. Not liking the taste of water is one reason for not drinking it enough, another reason is that drinking water is just not a habit – people forget to drink.

Here are some suggestions on how to make a habit of drinking water:

  • Have a 0,5 liter (2 cups) bottle of water with you at work. Fill it in the morning and drink it by lunch. Fill the bottle again and drink it during the afternoon before leaving home from work.
  • Do the same at home in the evening: Drink one to two 0,5 liter (2 cups) glasses of water during the evening while you’re cooking, watching TV or doing other activities.
  • Start your morning by drinking a glass of water.

Conclusion and general guidelines

There will always be different opinions about what is a good amount of water to drink a day but you really can’t go very wrong by following these simple guidelines:

  • If you are thirsty, drink
  • Try to drink about 2 liters (8 – 9 cups) of fluids a day
  • Drink more water while you exercise (before, during and after)
  • Check the color of your urine occasionally – it should not be darker than light yellow. If it is, have a drink!

How much water do you drink? Do you think it’s enough for you or do you try to drink more?




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