An infrared (IR) sauna uses electromagnetic light waves to generate heat, which is absorbed directly by the skin rather than warming the air around you. This process raises the body’s core temperature, initiating a measurable metabolic response. The passive heat exposure causes the body to expend energy in its effort to regulate temperature, confirming that a sauna session does result in some calorie burn.
The Body’s Thermoregulatory Response
The body maintains a stable internal temperature, and exposure to intense external heat triggers an automatic, involuntary cooling process. This defense mechanism is the direct source of the energy expenditure during an infrared sauna session. The heat stress causes the hypothalamus, the body’s internal thermostat, to signal an urgent need to dissipate heat.
One of the first responses is peripheral vasodilation, where blood vessels near the skin’s surface widen significantly. This action redirects blood flow from the body’s core to the periphery, allowing heat to escape through the skin. To maintain adequate blood pressure and circulation while blood is redistributed, the heart rate increases substantially, often mimicking the cardiovascular demands of moderate physical activity.
The body also activates the sweat glands, initiating profuse sweating as a highly efficient means of evaporative cooling. This entire internal workload—the increased cardiac output and the energy required for sweat production—demands fuel. The energy required to power this massive thermoregulatory effort is drawn from the body’s stored resources, which translates directly to a calorie burn.
Actual Calorie Expenditure in Infrared Saunas
The amount of calories burned during an infrared sauna session depends on numerous factors, including the duration, the ambient temperature, and individual metabolism. Scientific estimates for a 30-minute infrared sauna session suggest a calorie expenditure ranging from approximately 200 to 600 calories. This passive expenditure is comparable to the energy used during light activities such as brisk walking or gently swimming.
It is important to distinguish between actual energy expenditure and temporary weight loss observed immediately after a session. Weight “lost” post-sauna is temporary fluid loss through sweating, which is quickly regained upon rehydration. While the increased heart rate and thermogenesis consume stored energy, the sauna should be viewed as a supplement to, not a replacement for, regular exercise for sustained weight management.
The consistent heat exposure can stimulate the metabolic rate and increase the body’s core temperature, which has been linked to long-term body composition changes. One study noted that participants using an infrared sauna three times a week experienced a reduction in body fat percentage. The benefit is not solely in the immediate calorie burn but also in the systemic effects on metabolism and cardiovascular health that occur over time.
Comparing Infrared and Traditional Saunas
The primary difference between infrared and traditional saunas lies in the mechanism used to generate and deliver heat. Traditional saunas typically use a stove or heater to warm the air to extremely high temperatures, often between 165°F and 210°F. Conversely, infrared saunas operate at much lower air temperatures, usually between 120°F and 140°F, as the infrared emitters directly warm the body’s tissues.
Proponents of infrared technology suggest the deeper tissue penetration of radiant heat leads to a more efficient rise in core temperature. This theoretically induces a stronger thermoregulatory response at a more comfortable ambient temperature, potentially allowing for longer sessions. Studies sometimes show a slightly higher calculated calorie expenditure for infrared saunas, but the difference is not substantial enough to be a deciding factor.
Ultimately, the body’s physiological response—vasodilation, increased heart rate, and sweating—is triggered by the rise in core body temperature, regardless of the heat source. Since both sauna types achieve a similar thermal stress when used appropriately, the resulting calorie burn and cardiovascular effects are comparable. The choice often comes down to personal tolerance for high ambient air temperatures and session comfort.