How much do I need to drink for adequate hydration?

When we think of the gold standard for health and performance, we ideally want to be adequately hydrated on all days, at all times. Being dehydrated can have significant impacts on energy, cognitive function and appetite regulation, but being over-hydrated can have similar side effects. So how much DO we need to drink per day?

Dehydration of as little as 2% loss of body weight results in impaired physiological responses and performance. The reported health effects of chronic (long-term) mild dehydration and poor fluid intake include increased risk of kidney stones, urinary tract cancers and colon cancer. In saying this, there are also significant short-term effects on both mental and physical performance.

These include:

-              Fatigue

-              Impaired cognition

-              Gastrointestinal issues

-              Increased resting heart rate

So how can we tell if we’re dehydrated? To do this we use the WUT model (weight, urine, thirst). This model looks at 3 different components that, when 2 or more symptoms are present, there is a strong chance you are dehydrated.

1.        Weight: Greater than 1% of usual body mass loss compared to your typical morning weight

2.        Urine: Urine colour >4 on the colour chart

3.        Thirst: Perceived thirst sensation (feel thirsty)

For most adults, 10 cups per day of fluids may be enough to prevent these symptoms (including plain water, milk and low caffeine beverages).

A general guide is to multiply your body weight (kg) by 30-35 and that is your recommended fluid intake in mL/day BEFORE exercise (and ideally from water).

To calculate how much additional fluids you need to rehydrate from your training sessions, follow the protocol below:

1.        Weigh yourself BEFORE your training session (make sure you go to the bathroom before you weight yourself if you need)

2.        Measure how much water is in your bottle

3.        Attend your training session and drink all of the water you brought with you

4.        Weigh yourself AFTER your training session

5.        Calculate the weight difference from before your session to after your session

6.        Subtract how much water you drank from this number

7.        Multiply the final number by 1.5

8.        This is how much you need to drink to rehydrate from that session!