Let's take a lead from good old Cristiano Ronaldo today, and let's talk about hydration, specifically water.
Most of the time when people (and coaches) discuss nutrition and the importance of a healthy, balanced diet, we are thinking about calories and macronutrients (carbs, proteins and fats). And that, of course, makes sense, because your brain and your muscles need energy (typically derived from the carbs and fats you consume) to do what they do.
However, there is another important factor in our body's ability to perform - water. Although water has no energy, it is essential for our body to function properly.
What's the big deal?
Our bodies' cells consist mostly of water, and thus having too little of it will have an immediate and significant impact on your performance and health. If you are even mildly dehydrated, problems arise such as:
Tell me what to do, Coach!
To avoid these impacts and hydrate optimally, aim to drink about 2 to 2.5 liters of water during the first 10 hours of your day, which comes out to about one glass per hour.
Personally, I like (and feel as if I need) to get two or even three big glasses of water in my system immediately after waking up, as I always feel very thirsty after not drinking anything for the 8+ hours of time in bed, but you may have different preferences, so as long as you aim for getting in 2 or more liters by mid to late afternoon, you should be fine.
Why the first 10 hours? Why not anytime in the day?
During the first 10 hours after waking, the kidneys filter fluids efficiently, whereas later in the day the output is reduced, so you might find yourself waking up in the middle of the night to…you know.
If this is a frequent occurrence, try to hydrate during the day, limit fluid intake 2-3 hours before sleep, and if drinking at night, sip slowly. The rate and amount of fluid can influence the need to urinate.
Do you need to drink more when exercising and/or in hot weather?
The obvious answer is: yes. But how much more exactly?
In addition to the 2+ liters mentioned earlier, as a guideline while exercising, use the Galpin Equation:
Consume your body weight (in kg) × 2 in mL every 15-20 mins. In hot temperatures or while sweating, increase the amount by 50-100%.
So a 75kg man (e.g. me) should consume about 150ml for every 15-20 minutes of exercising, or about 500ml per hour.
Are there any other factors that impact hydration needs?
There certainly are plenty, but one that is probably relevant to a lot of people out there is caffeine intake.
Caffeine is a diuretic, so rather than aid in your hydration, it dehydrates your body. Thus, aim to drink 2x the amount of water (if possible with electrolytes like sodium, potassium and magnesium) as caffeine you consume to prevent dehydration. For example, for every cup of coffee, drink two glasses of water with low/no-sugar electrolytes, or add a pinch of salt.
And so, while the debate over whether Ronaldo or Messi is the greatest football player in the world may rage on, there really should be no debate about throwing out the Coca Cola and reaching for the Agua!
Source: Huberman Labs