Weight loss session starts at a high intensity to stimulate the cardiovascular system then reduces to a medium level. As the body works to cool itself, there is an increase in heart rate, cardiac output and metabolic rate similar to exercise. Perspiring is part of the complex thermoregulatory process of the body that increases the heart rate, cardiac output, and metabolic rate causing the body to burn calories.  Studies have shown that a 30 minute infrared sauna session can burn an upwards of 600 calories!  A 2009 study indicated that Sunlighten infrared saunas can lower weight and waist circumference in just a 3-month period.