People burn 50 to 100 percent more calories while sitting in a sauna than while sitting in a comfortable room, according to Fitness Blender. As a result, a healthy person who burns 35 calories per hour at rest burns approximately 52 to 70 calories while sitting in a sauna.
The human body burns calories to keep the heart pumping, metabolize food, maintain body temperature and perform other tasks. When healthy people sit in saunas, they sweat, which takes a significant amount of energy, especially over long periods of time. The energy lost to sweating causes the body to burn more calories than normal. However, even mild exercise is far more effective at burning calories than sitting in a sauna.