An infrared (IR) sauna is a heat therapy device that uses specialized lamps to emit electromagnetic radiation, which the body absorbs as heat. Unlike a traditional sauna, which heats the air, infrared waves penetrate the skin to warm the body directly at a lower ambient temperature, typically between 113°F and 140°F (45°C to 60°C). This distinction in the heating mechanism is important for understanding the physiological claims surrounding calorie expenditure. This article investigates the widely circulated claims that simply sitting in an IR sauna can lead to significant calorie burn.
How the Body Uses Energy in an Infrared Sauna
The energy expenditure in an infrared sauna results from the body’s system of thermoregulation. When infrared heat raises the internal body temperature, the body perceives this as a threat to its core thermal balance and works instinctively to correct it. This response initiates physiological processes designed to cool the body down, which accounts for the measurable metabolic boost.
The body’s primary cooling mechanism is increasing blood flow to the skin’s surface (vasodilation) and activating the sweat glands. This response forces the heart to pump faster, leading to an elevated heart rate that mimics low-level physical activity. The metabolic energy required to sustain this increased heart rate and produce sweat represents the calories burned during the session.
The passive heat stress temporarily increases the metabolic rate. The body continuously spends energy to maintain its internal temperature within a safe range. This mechanism explains why calories are burned without engaging in muscular movement.
Reported Calorie Burn Estimates
The figures most often cited for the calorie burn in an infrared sauna vary widely, ranging from approximately 200 to 600 calories for a 30-minute session. These higher figures are often associated with manufacturer claims and anecdotal reports, suggesting expenditure comparable to a moderate jog. However, scientific consensus suggests a more realistic burn of 100 to 200 calories for a typical 30-minute session.
This disparity highlights the limitations in obtaining precise data on metabolic expenditure during passive heating. The actual number of calories consumed depends heavily on several individual factors, including the user’s body weight, muscle mass, and baseline metabolic rate.
Furthermore, variables specific to the session itself, such as the sauna’s temperature and the duration of exposure, also significantly influence the total caloric cost. A study examining four successive 10-minute sessions in a dry sauna showed an energy expenditure totaling around 413 calories. The energy expenditure is real, but the magnitude is often overstated in marketing materials.
Why Infrared Sauna Use Is Not Exercise
It is important to distinguish the passive calorie expenditure in an infrared sauna from the active calorie burn achieved through physical exercise. Active exercise involves muscle contraction and movement, leading to a direct and significant energy demand that builds cardiovascular fitness and muscle strength. The sauna’s burn is a passive energy cost incurred solely by the body’s effort to regulate temperature.
The immediate drop in weight observed after a sauna session is due to the loss of water through sweat, not the consumption of stored body fat. This fluid loss is temporary and quickly reversed once the user rehydrates, which is necessary for safety. Although the physiological response to heat stress, such as an increased heart rate, mimics some aspects of cardiovascular exercise, it does not provide the same long-term benefits for cardiorespiratory fitness or muscle development.
Infrared sauna use functions as a supportive wellness tool that contributes to a minor metabolic increase. It should not be considered a substitute for a comprehensive regimen of diet and physical activity. The heat exposure provides benefits like relaxation and muscle recovery, but it is not a mechanism for sustained fat loss.