As you relax in an IR sauna, your body is actually hard at work producing sweat, pumping blood, and burning calories.
As your body increases sweat production to cool itself, your heart will work harder to pump blood at a greater rate to boost circulation.
This increase in your metabolism will burn calories. According to the Journal of the American Medical Association, regular use of an IR sauna imparts a similar stress on the cardiovascular system as that of running.
Regular use may be as effective a means of cardiovascular conditioning and burning of calories as regular exercise.