How much water should I drink each day?

A simple question. Surprisingly hard to answer.

There are no global, evidence-based guidelines for athletes.
And the classic “8 glasses a day” rule?
Isn’t based on any real evidence.

In sports nutrition, “hydration” has almost become shorthand for electrolytes.

But before we optimise sodium, we need to understand how much fluid the body actually needs.

Some of the best data we have come from Yamada et al. (Science, 2022) – using the gold-standard isotope tracing method in 5,000+ people across 26 countries.