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In all my years of fitness coaching, I think this is THE number one question I’ve been asked the most.  That and when to breathe during an exercise!  For something so simple, it’s also very complicated and understandably so.  My grandmother told me her doctor said that any fluid counts towards hydration including, caffeinated coffee and tea.  And some sources say you only really need to drink when you’re truly thirsty – but if that were true, I’d (personally) likely be dehydrated 90+ percent of the time, because I could sip on coffee (hot, or cold) all. day. long.  (*I wish that wasn’t true, but it is).

So, in my opinion, you can’t simply wing the water thing.  You do need to be intentional given your body is comprised of 60% water!  Yes, it’s true.  And if your cells are dehydrated – how in the heck can they do their job?!  Imagine an olympic marathon runner only drinking when they feel thirsty the week before their race – that would never happen.  Well then, imagine the massive marathon your digestive system runs every day … don’t you think it too should be well hydrated?  Yah, me too!

So then, how much is enough?!  How much water should you really drink in a day?

I’m going to keep this SUPER short for you girlfriend.

You need to consume 1/2 of your body weight (in pounds) in water (in ounces) per day!

Example –> 150 lb individual

150 (weight in pounds) / 2 = 75 ounces 

75 ounces = 2.218 litres

So, if you round that up it equals 2 1/4 L

Now I do want to talk through a couple of things.

Compare these two women – Adele & Tracy.

  • Adele is a computer consultant (sitting 8 hours per day) –> Tracy is a post office worker who walks 25, 000 steps per day
  • Adele drinks 5 cups of coffee daily –> Tracy drinks herbal tea
  • Adele exercises 1 hour before work every morning –> Tracy considers her job exercise
  • Adele is a nursing mama, who pumps at work during her breaks –> Tracy does not have children

Woah – brain hurricane right?!  Just when you had the answer you were looking for, lol!

The truth – the equation above IS correct with a few little notes.

First, The only major exception to this formula is if you’re a nursing mama in which case the fluid requirement varies between mothers and the amount of breast milk they produce; HOWEVER, a good rule of thumb is to consume approximately 4L per day!  With that said, I personally drink between 6-7L per day for the first 2-3 weeks postpartum and here’s why:

  1. Milk supply is largely influenced during the first few weeks postpartum – so you want to make-sure you’re extra hydrated so you can fuel that milk train.
  2. Delivery/recovery is no joke – it is the mother of all sporting events; so I treat it like the biggest race I’m ever going to run (and what is the first think you usually do at the end of a race, chug back the fluids).
  3. Hormone fluctuations are rampant during the postpartum period, but especially during those first few weeks – so hydration helps with any extra fluid loss due to night sweats, and other hormonal shifts.

*After the 3-week (‘ish) mark – I generally shift to a more modest amount of fluid -> the 4L/day recommendation!

For everyone else – the above formula is a reliable rule of thumb and pretty on par with research-based suggestions.

For example, The National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is about 11.5 cups (2.7 litres) of fluids a day (for women).  Note that said “fluid” not water.  Water-packed fruits and vegetables count towards this goal, so if you use the body weight/2 formula plus you consume fresh produce – it’s pretty much the same.  Furthermore, the “drink 8 x 8 ounce glasses of water/day” theory is close to 2L a day and just shy of the 2 1/4 we calculated for our 150 lb friend.

To keep things simple & to the point.  Aim for this:

2L of water-water (as in water, not produce)/day.

Add 1/2 L for every 30 minutes of exercise.

Match cup for cup water for every caffeinated beverage consumed.

Clear as mud?!  Yes, no – let me know 🙂

+ Happy Hydrating!




Beth Wall

Beth Wall created Osophē with a very specific purpose – to help provide women tools and resources to help them live their most energetic, vibrant, & uninhibited life. Personally she is a Believer, wife + mama (& coffee enthusiast). Professionally, she is a Kinesiologist, Certified Holistic Nutrition Practitioner, Certified Pre and Postnatal Coach and your biggest cheerleader!

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