Nutrition • 04.05.2015 • Vera Schwaiger

Stay Hydrated: Are You Drinking Enough Water?

That moment when your throat gets extremely dry and the only thing you want is a sip of cold water… I bet you know this feeling. Unfortunately, this signal is already too late according to nutrition experts. That thirsty feeling is actually a sign that you’ve failed at maintaining adequate hydration, which is why your body is now sending out alarm signals.

When doing sports, a constant liquid supply is vital as your muscle cells aren’t supplied with sufficient oxygen and nutrients if your body is lacking water. However, most people don’t know the amount of liquid to take in each day. Is it 1.5 or rather 3 liters? Here’s a few updates on drinking and hydration:

Runtastic water

What’s my daily liquid requirement?

As a general rule, most people can stick to the following recommendation:

  • 30ml x kg body weight = ml per day *
  • 15ml x lb body weight = ml per day *

* According to your personal needs and lifestyle, liquid intake recommendations range from 25 to 40ml per kg of body weight (or 12 to 18ml per lb of body weight). Remember, also foods rich in water (melons, cucumbers, soups, stews, etc.) are great liquid providers.

A man weighing 85 kg (187 lbs) would need approximately 2.5 liters per day – unless he’s doing sports, for example. In general, one should drink at least 1.5 but not necessarily more than 3.5 liters per day. Best case scenario: You drink regularly throughout the entire day, as your intestines can’t absorb more than 200 ml every 15 minutes.

Approximate fluid intake recommendation for active days

For fitness activities of 1 hour or more, we recommend additional hydration of…

  • 0.5 liters for moderate intensity
  • 1 liter for high intensity
  • 1.5 liters for extremely high intensity

per hour.

Keep in mind that you should drink even more the warmer it gets and the higher the altitude at which you’re being active.

More exact fluid intake recommendation for active days*

This is a tough one and we can’t give you an exact answer – but you can find out for yourself! Try this: Step on your scale before your run or workout (without clothes). Afterwards, go back for another weigh-in, then subtract your post-run weight from your pre-run weight and, if you’ve had something to drink, subtract the amount of liquid you’ve drank during your run. The result will be the amount of fluids you’ve lost (sweat in liters = weight difference in kg). Then, multiply this number by 1.5 and you’ll get your hydration recommendation!

Let me illustrate this with an example:

Before a 6K run at approximately 12°C / 54°F a runner weighs 65.7 kg, right after the run the scale shows 65.3 kg (both measurements were taken without clothes; he didn’t drink during the run).
The fluid loss (sweat) can be calculated by subtracting the post-run weight from the pre-run weight:
65.7 – 65.3 = 0.4 kg = 400 g → 400 ml

In order to establish an optimal hydration recommendation for this training session, we have to multiply this amount by 1.5:
400 x 1.5 = 600 ml

What should I drink?

Opt for water or unsweetened teas. For more active days, you can choose some (home-made) sports drinks or certain mineral waters.

When hustling from point A to point B and from one appointment to the next, we often forget to stop and take a few sips of water. Try to bring along a bottle of water wherever you go – no matter if in your handbag or the trunk of your car. This will help you stay hydrated. Cheers!

Bye for now,

* Did you know that the Runtastic app calculates your hydration needs after your activity? This calculation differs a bit from the one in the app (since we don’t know your exact pre- and post-workout weight), but both are a great way to find out how much you should drink after your session.


Vera Schwaiger

Vera has a background in dietetics and psychotherapy and lives her life according to what Einstein once said: “Life is like riding a bicycle. To keep your balance, you must keep moving.” For Vera, balance comes from mindfulness and healthy habits. Each day is its own journey and a new opportunity to improve. She approaches life step by step, always moving forward.

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  • Runtastic Team

    Hi Thomas, thanks for your input! 🙂