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Busting the "8 Glasses a Day" Myth


In one of our recent exercise nutrition workshops, the topic of hydration came up; “How much water do I actually need to drink?” Staying hydrated is essential for bodily function, and may be at the top of your mind now that the days are getting longer and warmer.

Why do we need fluid? Fluid plays important roles in the body, including:

  • Managing body temperature

  • Helping with digestion

  • Facilitating absorption and transport of nutrients throughout the body

  • Flushing out waste products from the body

  • Keeps bowel movements regular and soft

  • Cushioning organs and joints

If you’ve ever wondered about hydration and fluid intake, you’ve probably heard the “8 glasses of water a day” rule… but is it true?

Let’s break it down.

The first thing to keep in mind for staying hydrated is to identify sources of fluid - and they aren’t just water! Milk, tea, coffee, juice, broth, soup, and even pop count towards your daily fluid intake. Juice and pop contain similar amounts of sugar (~23 g or ~6 tsp for 1 cup). Although juice also contains some vitamins and minerals, we would not recommend using juice or pop as your regular fluid sources due to their high sugar content. There are other, healthier options such as water, milk and milk alternatives, or tea.

  • Water is a great thirst-quenching option because it has 0 calories and no added sugar or fat. It also has the added bonus of being free (if you drink from the tap).

  • Milk (and alternatives like soy milk) is a good source of protein, calcium, and vitamin D.

  • Tea and coffee can also be healthy beverage options, as long as you are aware of what you are adding to them (cream and sugar, for example).

Now that we’ve identified sources of fluid, how do we know how much we need to drink?

Fluid intake and staying hydrated varies widely. How much fluid you need varies from person to person, but also from time to time. Variability in fluid intake can be due to:

  • Differences in genetic makeup - everyone is different!

  • Men tend to require more fluid than women

  • The weather (i.e. the hotter it is, the more fluid you’ll likely need)

  • If you’re exercising and sweating

  • Athletes’ fluid needs vary widely, and only drinking plain water during training or competitions may actually be harmful or even dangerous. Book an appointment with Alex or Stephanie today if you are an athlete to talk about your specific fluid needs!

  • If you’re sick and experiencing diarrhea and/or vomiting

  • If you’re pregnant or breastfeeding

  • Book an appointment with Alex or Stephanie today if you are pregnant or breastfeeding to chat more about your individual needs!

  • If you have a medical condition which may affect your fluid needs (e.g. urinary tract infections, kidney stones, heart failure, kidney disease, cystic fibrosis, etc.).

  • Book an appointment with Alex or Stephanie today if you have been diagnosed with any of these to talk more about your specific fluid needs!

So while 8 glasses of fluid per day may be enough for the average, healthy adult; it may not be sufficient for others.

How can we know we are getting enough fluid? The easiest way to know how much you need to drink, is to check the colour of your urine! Checking that your urine is a pale-yellow colour is the easiest way to assess your hydration.

Here are some signs you might be dehydrated or may need to drink more fluids:

  • Feeling thirsty or even hungry

  • Sometimes our body cues can get confusing and when we are feeling hungry it may actually be thirst

  • Try drinking a glass of water when you start to feel hungry, then re-assess how you’re feeling ~20 minutes later

  • You are peeing infrequently, with very little output, and/or your urine is dark yellow or brown in colour

  • Constipation

  • Feelings of dry mouth or chapping lips

  • Headache, fatigue, dizziness, flushed skin, irritability, low blood pressure

Here are some ways to make sure you are staying adequately hydrated throughout the day:

  • Carry a water bottle with you wherever you go (at school, at work, at the gym, or even in the car). You’ll be amazed at how much water you drink naturally, just by having it within reaching distance!

  • Start your morning with a glass of water, before having breakfast.

  • Drink a glass of water before and with all of your meals and snacks. This can also help with portion control!

  • Include fluids before, during, and after exercise

  • Change things up!

  • Try sparkling water instead of plain.

  • Flavour your water with a slice of lemon or lime, adding other fresh fruit (such as grapefruit, watermelon, or cucumber), or herbs (like basil or mint).

  • You may also like sugarless flavour packets that can be found in store.

If you’re concerned about your fluid intake, or want to learn more about your specific fluid needs, book an appointment with Alex or Stephanie today!


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