Whole Body Cryotherapy (WBC) involves briefly exposing the body to extremely cold temperatures, typically ranging from -200°F to -300°F, for two to four minutes. This practice has grown popular, often promoted with the assertion that a single session can burn 500 calories. This claim suggests the short exposure is equivalent to a significant workout, positioning cryotherapy as a passive method for substantial energy expenditure. Evaluating the accuracy of this specific calorie-burning figure requires understanding the body’s physiological response to this intense cold.
How Extreme Cold Affects Metabolic Rate
The body’s immediate response to extreme cold is to initiate thermogenesis, the internal generation of heat to protect the core temperature. This protective reaction is regulated by the nervous system and involves a rapid increase in metabolic activity. The primary mechanism involved is Non-Shivering Thermogenesis (NST), which generates heat without involuntary muscle contractions (shivering).
A key player in this heat production is Brown Adipose Tissue (BAT), often referred to as brown fat. Unlike white fat, which stores energy, BAT is highly specialized to burn calories (fats and sugars) to create heat. Exposure to cold activates BAT, prompting it to increase its metabolic rate significantly.
This activation causes an increase in the production of uncoupling protein 1 (UCP1) within the mitochondria of brown fat cells. UCP1 uncouples energy production from the creation of ATP, diverting the energy directly into heat. The cold also stimulates the release of norepinephrine, which further fuels BAT activity and helps convert some white fat into more metabolically active beige or brown-like fat over time.
The Reality of Calorie Burn During a Session
The widely advertised figure of burning 500 calories during a single cryotherapy session is largely a misrepresentation of the total energetic response. Research focused strictly on the few minutes spent inside the cryochamber indicates the immediate calorie burn is quite low. The actual energy expenditure during the two-to-four-minute exposure is generally estimated to be only a few dozen calories, ranging from 5 to 150 calories.
The body’s exposure is too brief to allow for the sustained metabolic overhaul needed to burn hundreds of calories instantly. The 500-calorie figure often conflates the total, prolonged energy cost with the short duration of the session itself. Although the intense cold can increase the resting metabolic rate up to 350% during treatment, the time period is too short to translate into a 500-calorie deficit.
The overall calorie burn is highly dependent on individual factors, including body mass, existing brown fat, and metabolic efficiency. The main caloric benefit is not accrued during the three minutes of treatment. Instead, the true energy expenditure happens in the hours following the session as the body works to restore thermal balance.
Understanding the Post-Cryotherapy Metabolic Boost
The majority of the energy expenditure associated with cryotherapy occurs in the period following the session, often called the “afterburn effect.” Once the brief, intense cold exposure ends, the body must expend significant energy to return to its normal core temperature, a process known as rewarming. This metabolic recovery period can last for several hours.
This prolonged process requires the body to continue burning fuel to generate heat and restore homeostasis. The cumulative effect of the immediate cold shock and the sustained metabolic recovery accounts for the higher total calorie expenditure cited by promoters. Some sources suggest the total energy used by the body over the subsequent hours can reach the 500 to 800 calorie range.
This delayed effect means the benefit is a prolonged increase in the resting metabolic rate, not a quick burn. The 500-calorie claim is more accurately described as the total energy cost of the entire cold exposure event, measured over many hours, rather than the result of the brief time spent in the cryochamber. The physiological boost is real, but it is a sustained aftereffect.