The Goods

I Worked Out in a Gym That’s Kept at 50 Degrees. Should You?

Brrrn has opened a custom gym on the premise that you can optimize exercise by doing it in the cold.

An ice cube with a headband wrapped around it
Photo illustration by Lisa Larson-Walker. Photo by Poh Kim Yeoh/EyeEm/Getty Images, t_kimura/iStock/Getty Images Plus.

Well, Actually is a weekly column by Slate’s Shannon Palus. Each week, she’ll test health and wellness products to help readers figure out what they should try, what they should skip, and why.

“Did you sweat today?” asks a pink trucker hat on Etsy. “Sweating for the wedding,” a T-shirt declares. Lululemon has a membership program called the “Sweat Collective,” comprised of a combination of brand enthusiasts and Olympic athletes who are particularly committed to letting their bodies coat themselves in a film of liquid to cool down. There’s a chain of Philadelphia gyms simply called “Sweat Fitness.” On Instagram, #sweat has garnered nearly 13 million entries, mostly photos of disproportionately attractive people in attractive workout gear, almost none of whom appear to actually be perspiring.

Sweat is a biological reality of many a workout. It has also been co-opted into a badge of honor—a synonym for hard work, effort, even deservingness. Which is why it makes a sort of cyclical sense that a young boutique workout studio is attempting to differentiate itself with another emblem of effort: cold.

Brrrn, which opened its first (and so far only) location last year, is one of the quirkier bids in the world of boutique exercise classes. Brrrn’s custom gear includes winter hats, T-shirts accented with a blue snowflake, and Brrrn booties, which participants are required to wear for a portion of class. Its lobby features cozy wood paneling and rafters, evoking the inside of a lodge in upstate New York, where it held a team retreat for workout instructors in advance of opening. The workouts take place inside a room that’s chilled to 50 degrees; the door to the studio looks like that of an industrial freezer. I arrive at Brrrn on a March day that is already disappointingly cold and rainy. I change in a locker room—where a photo of Melissa McCarthy with her butt parked over a sink in that scene in Bridesmaids hangs beside rolls of toilet paper—and mentally steel myself to do high-intensity exercise while being chilly.

In the wild, cold weather is a wonderful temperature to work out in, as anyone who has run a late fall marathon, bundled up to head to a ski slope, or gone for an early-morning kayak can attest. But Brrrn is about much more than the pleasure of crisp air. It makes a pair of central arguments for going through the trouble of setting up a custom cooling system indoors: Cold can help you burn more calories, and it can allow you to work out harder, for longer, as the instructor tells me and my Brrrn-mates as we enter the studio.

Are either of these claims true? The first point was popularized by Ray Cronise, a NASA scientist turned entrepreneur, who—after noticing Michael Phelps’ svelte body, high-calorie diet, and cold pool workouts—lost a bunch of weight quickly through dieting, cold showers, and “shiver walks” in a T-shirt in below-freezing weather. Cronise’s “metabolic winter” hypothesis goes something like this: The evolution of our metabolism was marked by cold, and now, with modern technology, we are too warm and comfy for our own good. Cronise’s other claim to fame is worth mentioning, if only to counter the gravitas that “NASA scientist” lends him: He helped comedian Penn Jillette lose weight by encouraging him to eat only potatoes. The commercial efforts of others to create a calorie-burning cold fit into that kind of diet-silliness vein: shorts with ice-pack inserts (their website is now defunct), and a cold vest that can be worn to work under or over other clothing (the company announced it was going out of business in February), and of course, now, Brrrn.*

“The problem with cold, as I see it, is that people don’t like to be cold,” says Barbara Cannon, a professor emeritus at Stockholm University who studies how cold affects tissue in mice. Her work, to her surprise, has bolstered Brrrn’s mission—its website cites her research as evidence backing its approach. Being cold can result in losing weight—your body does have to burn extra calories to heat itself—but the length of time it takes to see meaningful weight loss is much longer than a workout class, and would be kind of uncomfortable. In Cannon’s experiments, mice in a 40 degree climate presented with an indulgent diet didn’t gain as much weight as their counterparts who hung out in a more comfortable climate. But the experience for the slightly svelter rodents involved a lot of shivering until their bodies adjusted by building up body-warming, calorie-burning brown fat. Humans experiments suggest that there’s some metabolic benefit to even milder cold exposure, as researcher Wouter van Marken Lichtenbelt has found. In a study of his, 24 participants hung out in 60 degree weather in shorts and a T-shirt for six hours a day over eight days, and they saw an increase in activity in the healthy brown fat that burns calories as it warms the body. But even with continued exposure in mice, the results were modest. “It’s exactly the same reasoning as with [regular] exercise,” Cannon explains—the cold mice compensated by eating more. “The effects are not dramatic.” Still, she does envision homes with lowered temps as one potential way to help, say, older folks from putting on weight as they age.

And what hasn’t been studied, in mice or in humans, is if their research applies when people are spending their time in the cold warming up via exercise or being bundled up in layers, as Brrrn instructs participants to do. Nor has anyone studied the effects of spending just a 50-minute class a couple times a week in the cold. “To do these studies costs money. There’s rectal thermometers involved,” says Johnny Adamic, Brrrn co-founder. He tells me that he conducted his own trial of sorts with a group of 16 people in a 30 degree freezer prior to opening Brrrn, asking a group of volunteers, which included former competitive athletes and friends of the co-founder’s mom, about their experience working out while rather chilled. (They reported being able to work out harder and longer.)

Tentative science aside, I love the weird world of branded fitness as much as anyone, and am excited to join in on the personal experimentation. I come ready for a “HIIT and Slide” class, one of just a couple of the studio’s offerings, in shorts and a hoodie. The 50 degree room feels surprisingly pleasant given the shitty weather outside—a little refreshing. It helps that we begin a warmup involving jumping and lunging. I quickly get toasty enough to shed a layer.

After some work with weights that feels very similar to standard-issue women’s-mag workout routines, it is time for the slide portion of the class, which is where the Brrrn booties come into play. They are basically giant socks that slip over your sneakers, allowing us to shimmy and propel ourselves side to side on the slippery boards, a motion that, to someone who has spent very little time on ice, might be like ice skating. I have trouble keeping my balance or going at more than one speed, which is a problem because at many points the instructor shouts at us to go as fast as we can. A noble goal under normal workout circumstances, but at Brrrn, on my precarious slide board, I feel like a drunk baby penguin.

Both Brrrn and the science agree on one clear thing about cold: “What happens with exercise in the cold is you can sustain it longer,” Lichtenbelt tells me. You can also push yourself to work harder: In a study of marathon runners, those racing in cool temperatures consistently had faster times. I am not sure that I want to sustain the penguin skating longer—cold weather might be beneficial for endurance, but it doesn’t reduce the friction of my slide board or keep me entertained during the rote motions.

The problem with Brrrn and its snowflake-adorned gear is the same problem I have with “sweating for the wedding” tank tops: Exercise is presented primarily as a means to a physical end, weight loss, a promise that it almost certainly cannot fulfill terribly meaningfully in either case. But I’m not working out to craft my body into an evermore finely tuned machine. The main reason I like working out is because of the sheer joy of it. While a crisp climate will always feel nice, thinking about how many more calories I could be brrrn-ing is actually just annoying.

People working out in a Brrrn gym
Brendan McCarthy


Time investment: 50 min.
Value: Low
Effectiveness: Pretty much regular exercise
Delightfulness: The temperature is nice!
Recommendation: Go outside

Correction, April 19, 2019: This piece originally misstated that Ray Cronise invented shorts with ice-pack inserts, cold vests, and Brrrn. These were not his inventions.