“I was worried I had cancer,” Emily says, “and she was turning it into a teachable moment about my weight.”

Other physicians sincerely believe that shaming fat people is the best way to motivate them to lose weight. “It’s the last area of medicine where we prescribe tough love,” says Mayo Clinic researcher Sean Phelan.

In a 2013 journal article, bioethicist Daniel Callahan argued for more stigma against fat people. “People don’t realize that they are obese or if they do realize it, it’s not enough to stir them to do anything about it,” he tells me. Shame helped him kick his cigarette habit, he argues, so it should work for obesity too.

This belief is cartoonishly out of step with a generation of research into obesity and human behavior. As one of the (many) stigma researchers who responded to Callahan’s article pointed out, shaming smokers and drug users with D.A.R.E.-style “just say no” messages may have actually increased substance abuse by making addicts less likely to bring up their habit with their doctors and family members.

Plus, rather obviously, smoking is a behavior; being fat is not. Jody Dushay, an endocrinologist and obesity specialist at Beth Israel Deaconess Medical Center in Boston, says most of her patients have tried dozens of diets and have lost and regained hundreds of pounds before they come to her. Telling them to try again, but in harsher terms, only sets them up to fail and then blame themselves.

Not all physicians set out to denigrate their fat patients, of course; some of them do damage because of subtler, more unconscious biases. Most doctors, for example, are fit—“If you go to an obesity conference, good luck trying to get a treadmill at 5 a.m.,” Dushay says—and have spent more than a decade of their lives in the high-stakes, high-stress bubble of medical schools. According to several studies, thin doctors are more confident in their recommendations, expect their patients to lose more weight and are more likely to think dieting is easy. Sarah (not her real name), a tech CEO in New England, once told her doctor that she was having trouble eating less throughout the day. “Look at me,” her doctor said. “I had one egg for breakfast and I feel fine.”