Like snoring and the ability to curl your tongue, some people have salty sweat that leaves white streaks behind, and others simply don’t. These things are often determined by genetics and natural variations, but there are a multitude of other factors that could be making your sweat salty—but what are they, and should you be concerned?
For starters, bigger people produce more sweat; it’s just a fact of life. While sweat volume and saltiness was once thought to be determined by sex, new research demonstrates that body size is a more accurate predictor, which often correlates with sex. Still, this does not mean that exceptions don’t exist, as other factors, such as DNA, play an equally important role.
You also may feel more sweat on your skin if your live and exercise in a drier climate. This is because the moisture on your skin, including sweat, evaporates faster in lower humidity, leaving more salt behind. In higher humidity, the skin stays damp from the moisture in the air for longer, and so less salt is left behind. Salty grit is more likely to be left on your skin during the first few scorchers of the year or during your first few days in a hotter climate because your body hasn’t yet acclimated to the hotter conditions, and will dilute the sweat as it adapts.
Diet and physical fitness also have a lot to do with the salt content of your sweat. If you eat a lot of salty foods, your sweat will likely have a higher sodium content. This isn’t necessarily bad, as your kidneys would filter out the salt that you’re sweating out anyway. This sodium that is released in sweat is one of four electrolytes that we need to keep our cells balanced and hydrated and is actually the most abundant of the four (the others being potassium, calcium, and magnesium, in order of abundance in the body). It is for this reason that our sweat glands naturally try to pull as much sodium as they can back into our bodies right as the sweat is about to pass through it in an attempt to conserve electrolytes. This is where your own fitness comes in. The more you work out, the more efficient your sweat glands become at conserving the sodium in your sweat. This ability changes if we change our workout conditions or take a break from exercise, says Lacy Alexander, Ph.D., associate professor of kinesiology at Pennsylvania State University, and means that we should be extra conscious about replacing the electrolytes we use during workouts.