Meanwhile, Wouter van Marken Lichtenbelt, a professor at Maastricht University, in the Netherlands, has headed up a spate of recent research on the weight-loss effects of “non-shivering thermogenesis,” the technical name for the calorie-burning, heat-generating metabolic phenomenon that occurs in the mild cold that Cronise champions. “Mild cold exposure increases body energy expenditure without shivering and without compromising our precious comfort,” Lichtenbelt and colleagues wrote in an April paper.

Cronise is currently testing whether, with a low-calorie diet and a cool environment, he can maintain a healthy weight and low body-fat ratio without going to the gym. He does not turn on the heat in his Alabama home until the coldest days of winter, which at times means letting the indoor temperature dip into the 50s. And he has—most amazing, to me—trained himself to sleep without blankets. When he talks about the practice, he uses blanket as a verb, as in: People used to blanket because bedrooms had no heat. Now we heat bedrooms and we blanket.

Even on the hottest nights, I feel like I need the weight of a blanket, or at least a sheet, to sleep. But like eating sweets or turning up the heat, he sees sheeting and blanketing as acquired habits that can be changed. He was able to wean himself from blankets gradually, by learning to sleep with them first folded down partway, and then folded further, and then, eventually, all the way down to his feet. Cold really isn’t that miserable, he insists, once you’ve gone through withdrawal and adapted to it.

Cronise said that when people tell him they need a blanket to sleep, he asks them, “Do you walk around in a blanket all day?” (Given the choice, some of us would.) But Cronise is more affable and reasonable-sounding than his anti-blanket rhetoric might suggest. The mild cold exposure he advocates might be as simple as forgoing a jacket when you’re waffling over whether you need one, not layering cardigans over flannels despite the insistence of the fall catalogs, or turning off the space heater under your desk. And if you don’t want to annihilate the environment by running the air conditioner to get a taste of sweet, calorie-burning, metabolism-enhancing cold in the summer, there are devices like the ice vest, which really isn’t as terrible as it sounds.

“The first time you put it on, it’s a bit shocking, to be honest,” Wayne Hayes, the vest’s inventor, warned me. “You feel like, Holy shit, this is cold.” But after wearing it a few times, he said, most people barely notice they have it on. That was my experience. (Hayes’s wife has become so used to the vest that she wears it under her clothes instead of over them.) Hayes recommends wearing the vest twice a day until the ice melts—which can take an hour or longer—though he has himself worn it as many as three or four times in a single day.

“If you buy more than one,” he said, drifting into salesman mode, and only half kidding, “you can cycle them throughout the day and wear them every waking hour.”