What sauna-goerslose in the sauna —and need back.
At SAUNACHELIN 2018–2025 award-winning saunas
Do you know how much we sweat over three sauna sets?
That sweat carries not only water but also salt and other electrolytes — and the sauna room and the cold bath are time when you can't drink. Kabaya's Enbun Charge is a tablet candy to enjoy in all kinds of moments when you sweat.
From November 11 — Totonoe no Hi — SAUNACHELIN award-winning saunas will begin handing out the Sauna Support Kit. A new sauna habit, starting at the saunas we've awarded.
So the science doesn't stop at knowing. A 4-piece Enbun Charge sample, paired with a Q&A leaflet on sauna and salt. From knowing to doing.
Opens Kabaya's website
What do we sauna-goers lose, how much, and how should we replace it? We asked sauna doctor Yasutaka Kato.
The weight you drop right after a sauna comes mainly from a temporary loss of water. Even in a study of 12 sessions at 90°C or above over four weeks, there was no significant change in body weight or body fat*.
In other words, most of the weight you lose is water that has left your body as sweat. It isn't weight you've lost — it's what you need to replace.
Results of a small-scale study.
An average visit lasts 76 minutes: 26 in the sauna room, 5 in the cold bath and 26 resting.
Most saunas don't allow eating or drinking in the sauna room or the cold bath, so 31 of those 76 minutes are time you can't drink. The moments you lose sweat and the moments you can make up for it are separate — that's what makes the sauna different.
Data: SAWATCH sauna smartwatch + Sanokuni app, August 2025 – July 2026
In winter, total time in the sauna room is about 5 minutes longer (23.9 min in July → 29.3 min in January), and estimated sweat rises by about 20%. Comparing the same people in winter and summer, more than 80% sweated more in winter. The number of sets barely changes — in colder months, people simply stay longer in each set.
Estimated sweat is calculated from body size and time spent in the sauna room.
Minerals and other electrolytes leave your body along with sweat. A rough guide to the salt equivalent lost over three sets is about 0.6 g*. If you drink a lot of plain water, the sodium in your blood becomes diluted, and your body flushes the water out as urine to keep its concentration. Taking water and minerals together really matters.
Sweat salt concentration was not measured; figures are converted using average values from the literature. Sweat concentration varies from person to person.
One tablet per 100 mL of water is a guide — the same salt concentration as 0.1% saline. If you drink 400–500 mL over three sets, 4–5 tablets is a guide.
Don't drink it all at once — keep each drink to about 200 mL. Add Enbun Charge along with your water.
Supervised byDr. Yasutaka KatoM.D., Ph.D., Representative Director, Japan Sauna SocietyBorn in Gunma Prefecture; graduated from the Hokkaido University School of Medicine. M.D., Ph.D. (pathology). After working as a specially appointed assistant professor at the Hokkaido University School of Medicine, moved to the United States to work at a Harvard Medical School teaching hospital, researching drug discovery for pancreatic cancer. Since returning to Japan, has practiced cancer genomic medicine at the cancer genomic medicine center of the Keio University School of Medicine and at the oncology research institute of Hokuto Hospital. Seeing medical costs rise ever faster, came to recognize the importance of preventive medicine, then founded the Japan Sauna Society to study sauna as preventive medicine, and 100plus Inc. to promote it. Author of Isha ga Oshieru Sauna no Kyokasho (Diamond, Inc.), with many media appearances including Fuji TV's Honma Dekka!? TV and Bungeishunju. Also the medical supervisor of the medical manga Fragile (Kodansha).
