Every explainer we've published on hydration science, organized by topic. No paywalls. No registration required.
The antidiuretic hormone system and aquaporin channels represent one of the most sophisticated homeostatic mechanisms in vertebrate biology. Here's how they work and why they matter for understanding hydration.
Osmoreceptors in the hypothalamus trigger thirst when blood osmolality rises. The problem is that this response can arrive after fluid deficit is already meaningful. What research says about relying on thirst alone.
Caffeine's diuretic effect is real but dose-dependent and substantially blunted by tolerance. A comprehensive look at what the controlled trials actually found when they compared coffee drinkers to water drinkers.
Cucumbers, watermelon, strawberries, and cooked oats all contain substantial water. For people eating varied diets, food-sourced fluid can account for a meaningful portion of daily intake. The data on common foods.
Exercise-associated hyponatremia has caused deaths at endurance events. Understanding the mechanism - dilution of blood sodium beyond the kidneys' excretion capacity - clarifies why "drink as much as possible" was always bad advice.
The Armstrong Hydration Color Chart has been validated in research settings as a field assessment tool. This explainer walks through what each level means, what confounds the reading, and when to look beyond color.
Sweat rate is determined by genetics, fitness level, heat acclimatization, and environmental conditions. Two people running side by side can have sweat rates that differ by a factor of three. What this means for replacement.
These minerals carry electrical charge through body fluids. Understanding what each one does and where it's found clarifies when diet is sufficient and when circumstances genuinely change the picture.
The National Academies and European Food Safety Authority have both published weight-adjusted fluid intake estimates. This explainer makes those numbers accessible and explains the assumptions behind them.
As the body adapts to heat over one to two weeks, sweat volume increases while sodium concentration in sweat decreases. This has real implications for how much electrolyte replacement is appropriate.
Alcohol suppresses ADH production, increasing urine output. The dehydrating effect is real. What's less clear is how much this contributes to next-day symptoms versus other mechanisms. Research review.
Several controlled studies have measured reaction time, working memory, and attention in dehydrated versus euhydrated participants. The results are more nuanced than headlines suggest. A careful look at the data.