Is spending time in a cold environment one of the keys to boosting
weight loss? It might help, because your body works harder in colder weather to maintain your internal body temperature, and this may result in additional calorie burn.
“In general, yes, people tend to burn more calories while in the cold,” due to your body’s natural cold-defense responses, says Cara Ocobock, PhD, an associate professor and the director of the Human Energetics Laboratory at Notre Dame University in Notre Dame, Indiana, who has studied the effects of frigid temperatures on exercise outcomes. “However, there is a great deal of variation in how many extra calories people expend,” she explains.
Whether
you’re exercising outdoors in winter or simply spending time in a cold environment, feeling chilly prompts the body to burn more calories by increasing
metabolism to better regulate body temperature, says
Dominique Gagnon, PhD, the director of the Helsinki Clinic for Sport and Exercise Medicine in Finland, who has researched the effects of temperature on metabolism during exercise.
This happens via thermoregulation, the process by which the body produces or releases heat to maintain its core temperature of around 98.6 degrees F, all controlled by a structure known as the hypothalamus in your brain.
When you’re cold, your body has to work harder to stay warm, which increases your
basal metabolic rate — or the speed at which it burns calories (energy) to perform necessary functions, such as breathing and digestion.
As a first line of defense against the cold, vasoconstriction occurs, which is where the blood vessels contract in an attempt to retain heat.
From there, two thermoregulation mechanisms, known as shivering and non-shivering thermogenesis, can kick in. “Both processes require fuel to make this happen, which leads to the increase in calorie burn,” Dr. Ocobock explains.
Non-shivering thermogenesis is how the body first attempts to generate heat
without muscle movement. It produces heat by activating
brown adipose tissue (BAT), or specialized brown fat cells that transfer energy from food and boost calorie burn. “BAT is a type of fat that burns only to keep you warm when you are cold-exposed,” explains Ocobock, adding that increasing BAT activity can lead to increased calorie burn.
Shivering thermogenesis happens next, generating heat through rapid, uncontrolled muscle contractions. “Shivering thermogenesis is the dominant form of heat production under cold stress,” Dr. Gagnon says.
“Shivering can produce up to five times the heat we generate from our resting state,” he adds, explaining that because muscles are one of the most metabolically active tissues in the body, they can generate warmth by burning fuel (or calories).
Together, these processes may contribute to weight loss. “You burn more calories in the cold,” says Caroline Apovian, MD, a professor of medicine and the codirector of the Center for Weight Management and Wellness at Harvard Medical School in Boston, explaining that both BAT activation and thermogenesis can lead to increased calorie burn.
One review of 10 randomized controlled trials out of China found that cold exposure significantly boosted calorie burn in healthy adults — with an average increase of around 188 calories a day from acute (short-term) exposure to around 60 degrees F, compared with room temperature environments.
But there are a number of factors at play that determine how many calories you burn while cold, Ocobock says. These include how cold it is outside, the clothing you’re wearing, and whether you’ve been previously acclimated to cold climates.
“For the mild cold exposure [typically around 60 degrees F, with little to no clothing] we use for BAT studies, there’s a range of 3 to 8.7 percent increase in calorie burn,” Ocobock says,
noting that among native cold climate populations, resting metabolic rate may be significantly higher than among temperate climate populations — though this also varies.
Colder temperatures (along with exercise) may lead to even greater calorie burn. In a small, older study conducted by Ocobock, 53 healthy adults took part in 12- to 16-week-long outdoor education courses, which included activities like hiking and cross-country skiing in 14 to 23 degree F weather at moderately high altitudes. Compared with exercise at mid-50-degree temperatures, participants burned significantly more calories. Specifically, the 37 male participants burned on average 4,787 calories per day in the winter, compared with 3,822 when exercising in the spring, and the 16 female participants burned on average 3,837 calories per day in the winter and 2,884 in the spring.
Cold exposure may support weight loss by turning hard-to-lose white fat (which tends to build up around the abdomen, buttocks, and thighs) into calorie-burning brown fat.
Even mild cold exposure (temperatures ranging from approximately 54 to 66 degrees F) appears to activate brown fat and increase the breakdown of stored body fat, suggests one review out of Switzerland of seven studies with 85 participants.
Gagnon says additional long-term studies are needed to learn more about exactly how much cold exposure may lead to significant weight loss. “Adding cold exposure may be a potential way to increase energy output, but it should be done in parallel with an exercise and food plan as cold exposure alone is unlikely to generate meaningful loss in weight,” he says.
Weight loss aside, research suggests there may be other health benefits to cold exposure. Some studies have shown that both one-time and repeated, deliberate acclimation to cold environments may help improve
insulin sensitivity and reduce fasting glucose (
blood sugar) levels in patients with
type 2 diabetes.
As one review notes, this tactic may be beneficial as a therapeutic strategy in type 2 diabetes and
obesity management. But more research is necessary.
Cold exposure via therapies like cold-water immersion may also have an impact on mood improvement, per one small study from the United Kingdom, where 33 healthy adults reported feeling more positive, active, alert, and attentive after a cold-water bathing session.
“There is something to be said about cold exposure and temperature alterations and effects on mood in a positive way,” says Dr. Apovian. “This may be one of the reasons why people in some countries [including the United States] use cold and hot tubs in health clubs — in addition to the purported effects on insulin sensitivity.”
Despite the potential calorie-burning benefits, experts generally agree that cold exposure isn’t an effective weight loss strategy on its own.
“I think it can be one tool in the toolbox for managing weight,” says Ocobock. “Cold exposure will not produce rapid massive changes in weight loss, especially if one is not combining it with
dietary changes.” That’s because any extra calories burned are typically modest, and can be counteracted by an increased appetite and reduction in physical activity levels — both of which tend to occur in colder or winter climates.
Moreover, extreme or repeated cold exposure may not be safe for everyone. People with
hypertension,
heart disease, and other underlying health conditions should check with a healthcare provider first, as the cold shock response can lead to
spikes in blood pressure and interfere with breathing, Ocobock notes.
Additionally, people who are pregnant are advised to steer clear of extreme cold to avoid possible adverse outcomes, including preterm birth and low birth weight.
While cold exposure may help burn extra calories, ultimately, it’s not as effective as other weight loss methods, says Ocobock. “Is it going to have the same impact as gastric bypass surgery or GLP-1 medications? No — but it is a tool that can be utilized,” she says. If you’re trying to lose weight, talk to your doctor or registered dietitian-nutritionist about the best method for you.
Rachel Green
Rachel Davis
Derek Schulz
Sophia Martinez
Dr. Amara Okafor