Body size, sex and weather explain little of how salty your sweat is
Across 1,944 sweat tests from 1,304 people, body size, sex, exercise mode, intensity and weather explained 17 to 23 percent of how salty sweat was. Salt in the diet explained none.
What the study found
What makes one person's sweat salty is mostly unexplained
A personalised-hydration questionnaire has little to work with. Across 1,944 sweat tests from 1,304 people, models built from body size, sex, exercise mode, intensity and weather explained 17 to 23 percent of how salty a person's sweat was. Dietary salt intake explained none of it.
The caveat · A sports-drink maker's own data
The analysis came out of a sports-drink manufacturer's own sweat-testing database, which cuts against the simplest commercial reading but travels with the finding either way. The people tested had chosen to come for sweat testing, so they skew athletic. Two of the three models used forearm patches, an indirect estimate; the whole-body method covered 48 tests. Unexplained variance includes measurement error, so this shows these variables do not predict sweat sodium, not that nothing could.