When you first put on the ice vest, you will feel cold. Not intolerably cold, but cold enough to make you think, What am I doing with my life? Or, at least, as numbness spreads across your shoulders and down your back, There must be better ways to lose weight. And there are. But as an adjunct to those better ways, the vest carries some unlikely promise.
The sturdy Han Solo–style garment is loaded with ice packs, and it’s inspired by a theory gathering momentum among scientists: namely, that environmental thermodynamics can be harnessed in pursuit of weight loss. The basic idea is that because your body uses energy to maintain a normal body temperature, exposure to cold expends calories. The vest’s inventor, Wayne B. Hayes, an associate professor at the University of California at Irvine, claims that wearing it for an hour burns up to 250 calories, though his data are very rough. A little more than a year ago, he began selling the vest, which he calls the Cold Shoulder, out of his Pasadena apartment. Name notwithstanding, people won’t ignore you when you wear it.
Ken K. Liu, a principal at a hedge fund in Los Angeles, has been wearing the vest under his suit jacket on and off for about a year. He told me that some people’s first reaction to the unwieldy getup is “What the hell are you doing?” As soon as Liu explains the concept, though, many of them say it sounds like a good idea. Others still think it’s “stupid”—as did my colleagues, when I wore one—but Liu has not been deterred. Each morning while his coffee is brewing, he takes his vest out of the freezer and dons it without shame. Liu was never “fat,” by his estimation, but he says he did carry a few extra pounds that he had trouble dropping, despite exercise and attention to diet. The Cold Shoulder closed that gap.