We have a complicated relationship with water. It makes up a significant amount of our cells. But making sure we drink enough can be a chore in the summer—and even more so in the winter. In fact, it turns out that cold temperatures put us at even higher risk for dehydration.
It doesn’t help that thirst tends to be a latent predictor of when hydration is needed—even when we lose more than 2 percent of our body mass. This makes maintaining fluid balance more difficult, and keeping the amount of electrolytes in various body fluids, such as blood and urine, within healthy ranges is essential to your body’s blood chemistry, muscle action and other processes. (Sodium, calcium, potassium, chlorine, phosphate and magnesium are all electrolytes.)
Add environmental temperature to the fluid-balance mix, and everything we thought we knew about hydration isn’t so clear. It turns out that winter, not summer, puts us at an increased risk of dehydration. When it’s cold, we lose water from breathing (there are water particles in our breath), and sweat evaporates quickly in cold, dry air—something that doesn’t happen when temperatures are warm.
Besides all this, cold alters our thirst sensation, according to research published in the journal Medicine & Science in Sports & Exercise. “People just don’t feel as thirsty when the weather is cold,” says lead researcher Robert Kenefick, Ph.D. “When they don’t feel thirsty, they don’t drink as much, and this can cause dehydration.”