We all know that body image is a national obsession, with every movie poster and magazine ad bombarding Americans with the message that slim people are beautiful. As a result, note the authors of a new study published in PLOS One, obese people often get the message that others perceive them as lazy, unsuccessful, and weak.

Predictably enough, all that fat-shaming hasn't inspired us to get trim and healthy; in fact, it's had the opposite effect. People interviewed for the study who were not obese when it began, in 2006, were two and a half times more likely to wind up obese four years later if they had faced some form of discrimination or humiliation related to their size. And those who started out obese were three times more likely to remain so if they were subjected to fat-shaming.

"Weight discrimination, in addition to being hurtful and demeaning, has real consequences for the individual's physical health," says study author Angelina Sutin, a psychologist and assistant professor at the Florida State University College of Medicine in Tallahassee, Fla.

The researchers have merely confirmed what we already knew — humiliation does no one any good. "So the takeaway from this is that being super negative to people will not yield positive results. Shocking!" says Tracie Egan Morrissey at Jezebel.

"Stigma and discrimination are really stressors, and, unfortunately, for many people, they're chronic stressors," Rebecca Puhl, deputy director of the Rudd Center for Food Policy and Obesity at Yale University, tells Today. "And we know that eating is a common reaction to stress and anxiety — that people often engage in more food consumption or more binge eating in response to stressors."

Still, notes Melissa Dahl at Today, many people — including some medical ethics professors — argue that people need to get some kind of negative messaging about obesity, because it can lead to serious health problems and even early death. One way to do that is to treat obesity as a disease, as the American Medical Association officially began doing last month. That gets across the need to combat obesity without getting personal about it.

Will that help? Maybe. Unhealthy eating and exercise habits develop over a lifetime, so improving them takes patience, experts say. One key, says Sy Mukherjee at Think Progress, is starting early, and being positive. "Having parents talk to their children about healthy nutrition habits," Mukherjee says, "is much more effective in curbing childhood obesity than talking to them about weight."