On a shivery winter Sunday in Manhattan, I was sweatier than I’d ever been in my life. I had been zipped into a heated bag during a visit to Shape House, a chain of “urban sweat lodges” with locations in Los Angeles and New York City. A confession: I smelled bad. My friend’s band had played a show the night before, which meant that wine and nachos were on the menu. It was an unimpeachable idea at the time, but one that added an extra challenge to luxuriating in a plasticized sleeping bag for 55 minutes the next morning. As the bag grew wet with merlot-scented perspiration, it felt like I was trapped in a hot cocoon of my own poor choices.
I hoped, at least, that I’d emerge slightly healthier, although my hope was tempered with skepticism. The wellness industry hypes tips, tricks, and fads at a disorienting pace, and I often find it tricky to unknot common sense from nonsense. Exercise, however, most everyone can agree upon: It is widely considered healthy. Exercise also makes people sweat. The idea that working out improves the body is as close to undisputed as it gets. But is sweating, in and of itself, a pathway to greater wellness?
To be clear, sweat serves an uncontested purpose as a bodily function. The eccrine sweat glands, found all over the body, help humans regulate body temperature by secreting odorless, salty fluids. Our apocrine sweat glands are the weirder cousin—found in the armpits, groin, ears, eyelids, and breasts, stimulated by emotional stress and puberty, and capable of enormous stank, they also thermoregulate. Scientists continue to search for other benefits to sweating. In 2001, a team of scientists in Germany found that sweat can contain an antimicrobial protein that may help stave off infection.
But I wasn’t at Shape House because I had hopes of warding off sickness through skin juices alone. I was there because of the other promises the company makes about the power of sweat. Shape House claims that its infrared heat experience provides “an intense, detoxifying, health-boosting sweat that helps you look and feel healthier, happier, and brighter.” The company attributes an eye-popping list of benefits to its service, from weight loss to reversing sun damage and the effects of aging on skin, to receiving the cardiovascular health advantages from a session equivalent to a 10-mile run.
To achieve this healthier, happier, brighter future, customers change into thin, grubby gray sweat suits provided by Shape House and are then nestled into what appears to be a weighty sleeping bag within a private booth by courteous attendants, with alkalized water placed at arm’s length. Headphones are provided to watch television as the bag heats up, lest anyone swelter without entertainment. (Netflix, HBO, Hulu, and a variety of other streaming services are available; I was also allowed to keep my phone.) Selena Gomez swears by it; Kourtney and Khloe Kardashian filmed a scene from Keeping Up With the Kardashians from within Shape House’s glowy, orange-tinted confines. The company has been successful enough business-wise to gain these ardent celebrity fans and to expand from Los Angeles to Manhattan this year. (Although, alas, not successful enough to come up with a better description for itself than “urban sweat lodge.”)
Shape House’s specific hot-blanket method of inducing sweat is novel, but the general idea that sitting around and sweating is a good thing that everyone should do is very old. Sweat lodges have long been used by indigenous North American cultures for purification rituals. (There are many still in existence today, and Canada’s Centre for Addiction and Mental Health opened up an actual urban sweat lodge for its patients in Toronto in 2016. Also, this year, the Boulder police told members of the Genízaro Apache nation that their sweat lodge ceremony violated city law, exacerbating ongoing tensions between the indigenous community and the city authorities. The incident serves as a stark reminder that not all sweat lodges are treated the same.)
Saunas have existed in Europe and Scandinavia since at least the Middle Ages; in Korea, references to bathhouses outfitted with heated rooms date back to the 14th century’s Joseon Dynasty. Group sweating approached grandeur in the bathhouses of ancient Rome, and in 2001, researchers concluded that they’d unearthed the ruins of a Mayan sweathouse from 900 BC. If people heating themselves up to feel good is a fad, it is a remarkably ancient one.
The Shape House experience, with its emphasis on television watching and infrared blankets, is decidedly modern and completely untethered from the cultural traditions its name evokes. Sweating occurs in private pods; it is an individual experience, not a communal one, and there’s no talk of spirituality. The tranquil decor mixed with the vaguely medical look of the sweating equipment gave the place a slightly unsettling antiseptic atmosphere, like a luxe laboratory. After my sweat, I was brought to a “relaxation lounge” outfitted with comfy toweled chairs and soothing music and offered a choice of tea or oranges. I chose the oranges.
“These will taste like the best thing you’ve ever eaten,” a spa attendant assured me. They were up there. I left the spa damp, glowing, and slightly woozy. I was definitely relaxed. It was less clear whether I was well.
In Finland, researchers conducted a study last year that suggested that sauna visits might lower the risk of developing memory diseases like Alzheimer’s. (Sweating in saunas is a national pastime in Finland, so this is a bit like The Wire superfans conducting an experiment to prove that The Wire is the best television show, but still.) “We have taken into account other lifestyle factors, like physical activity and socioeconomic factors,” Jari Laukkanen, senior researcher and a professor of clinical medicine at the University of Eastern Finland, told Reuters in 2017. “There is an independent effect of sauna on these outcomes.” While it’s unwise to draw conclusions from a single study, the researchers followed more than 2,300 middle-aged Finnish men for more than 20 years, and the large sample size and long period of observation bolster credibility.
I found the Shape House experience more pleasant than a sauna; the heat never approached oppressive temperatures, and I could zone out to the television. But its claims of sweat-induced wellness do not appear to be backed up by science.
“I know of nothing about sweating per se that is advantageous. Indeed, it might be argued it is potentially hazardous as it leads to dehydration and hypovolemia (low blood volume) with the risk of fainting,” physiology professor Mike Tipton, who works at the University of Portsmouth’s Extreme Environments Laboratory, told me by email.
“Sweat secretion (from an eccrine sweat gland) doesn’t remove toxins or ‘cleanse’ the body of waste products. Urine excretion (and to a lesser extent, bowel excretion) more likely removes the bulk of toxic byproducts from our body. With that said, we haven’t been able to effectively study the contents of sweat secretion well because it is so difficult to collect (in terms of volume and potential contamination) so HONESTLY we do not know,” Oakland University associate professor of exercise science Tamara Hew-Butler told me by email. “We often feel better after sweating, I suspect, from the associated vasodilation which makes us feel ‘flush,’ or increased metabolism from either exercising and/or heating up.” (Shape House did not respond to request for comment.)
When we talked on the phone, Hew-Butler was nonplussed by many of the claims Shape House makes about its treatments, particularly the claim that it can confer benefits similar to the cardiovascular advantages of going on a 10-mile run. “The only thing that might be plausible is that you would sweat similarly to running 10 miles,” she said. The claims about skincare benefits also left her skeptical. “You’re secreting a substance that is more water than salt, so maybe that in itself is cleansing,” she said. The “cleansing” benefits of sweating appear to boil down to the fact that your face gets wet.
“The claims seem to be a little bit too outlandish in my opinion,” Massachusetts Institute of Technology professor Patricia Christie, who specializes in biological chemistry, told me over the phone, emphasizing the need for proper hydration in situations where the skin gets salty to taste. Christie noted that Finnish communities often use saunas in their skincare routines. “The act of sweating and then loofahing is good for your skin, because it sloughs off the dead skin,” she noted, explaining that saunas had cachet as spaces for cleansing and grooming in the northern Ontario town she’d grown up in. But she was skeptical of claims that a Shape House session confers the same benefits of exercise. “That I don’t believe at all.”
Apart from its name, Shape House wasn’t unpleasant as a quirky recreational treatment. But it does cost $70 for a single session. (“Sounds like a scam,” Christie said when I mentioned the price.) Perhaps there will be breakthrough research in the future that proves the act of sitting and sweating is a panacea. Until this happens, the treatment is more of an expensive experimental spa field trip than a trustworthy addition to a health and fitness regimen. What’s more, it’s a treatment that requires careful attention to staying hydrated—and a desperate need for a shower afterward.