"They come to this moment where they’re excited that so many things have been positive in their life over the past several months," Dr. Butsch said. "And then they realize that they have been almost cheated, throughout their business relationship, and it puts a bad taste in their mouth about how they’ve been treated."

They tell him that within a few months of slimming down, they find themselves suddenly enjoying new recognition and promotions at work. Which is wonderful — until it hits them that their newfound success suggests that they were being discriminated against when they were heavier.

Dr. W. Scott Butsch, an obesity medicine specialist at Massachusetts General Hospital, keeps hearing deeply disturbing stories from patients who have lost lots of weight.

A growing body of research bears out those accounts of weight-based bias. Forty-three percent of overweight and obese people say they’ve experienced bias against them by their bosses, one study found. Another calculated that severely obese white women tend to earn 24 percent less than their normal-weight co-workers.

Dr. Butsch saw injustice compounded. His patients had been judged based on their weight, and their weight stemmed from what medical science increasingly understands as a disease, not a character flaw. He felt compelled to speak out: Earlier this year, he testified on behalf of a bill in the Massachusetts Legislature that would ban workplace discrimination based on weight.

Obesity specialist Dr. W. Scott Butsch (courtesy)

It was a somewhat quixotic move. The bill had been proposed every session for the last 15 years, and never gone anywhere.

But this year is different. Last month, the weight discrimination bill sailed through the committee that considered it, gaining easy approval in a 7-to-1 vote.

What changed?

"I think the key to this shift was research," said Rep. Byron Rushing, the Democrat and now House majority whip who has sponsored the bill for the last 15 years. "It was having academics who’ve been working in the field of obesity, having testimony from a medical doctor. To be able to say that in recent studies of discrimination against women, that a higher number of women report seeing discrimination based on their body shape than you have of women being discriminated against because of race. Those kinds of studies are giving people pause.”

Dr. Butsch notes that there’s also a far bigger scientific shift under way: from the old medical concept of obesity as a failure of willpower to the new understanding that it is a disease — a chronic and complex disease.

The old school portrays obesity as a psychological problem, a simple matter of self-discipline. "Just eat less and exercise more."

The new understanding of obesity sees it as a "dysregulation of energy," he says. It’s affected by genes and the environment; by the brain and the gut; by hormones with names like leptin and ghrelin and other physiology still to be discovered.

The American Medical Association officially recognized obesity as a disease in June, following the World Health Organization and other medical authorities. And as many millions of people know, it can be a very tough disease to beat.

"We think of obesity as one problem," said Dr. Butsch, an instructor of Harvard Medical School, "but I would challenge you to think that it’s a number of different types of obesity, much like we have in cancer."

"The treatment has to match the complexity of the disease. Just like in chemotherapy, where you have multiple regimens that somebody has to go on to cure cancer, the same thing is going to happen with obesity. It’s not going to be the one diet, it’s not going to be the one drug. It may not even be surgery. You see people who get surgery and it doesn’t cure their obesity."

He makes one more striking cancer comparison: For you to tell a friend struggling with weight, "You should try my diet — it worked for me," could be as irrelevant as a patient with one type of cancer telling a patient with another type, "You should try my chemotherapy — it worked for me."

At the legislative hearing where Dr. Butsch testified, so did Melinda Watman, founder of the "The F WORD FAT," a company that offers training and advocacy to combat “fat shaming” and weight bias.

She is 5'1" and before she had weight-loss surgery, she used to weigh 225 pounds.

Melinda Joy Watman (Courtesy)

“I remember being in New York on a subway and sitting down," she recalled in an interview, "and it’s tight, everybody’s squishing in, and just dirty looks. You know, 'Who’s this fat person sitting next to me?' With just utter contempt and disgust.”

That kind of thing, she says, "happens all the time." She calls body-weight bias "the last bastion of public humiliation, public discrimination. Nobody would call you on the table for doing it, subtly or grossly. It's like, 'Have at it. It's good clean fun.'"

At one point before she lost weight, Watman, a certified nurse-midwife, was a contender to be the director of a large nurse-midwifery practice, and didn’t get the job, despite strong credentials and endorsements from her peers.

"Can I absolutely, positively say it was because I had obesity? I can’t," she says. "What I can tell you is they brought in a woman who was a stranger to the organization, had half the experience I did, and was thin."

She has a one-word response to the stereotype of people with obesity as slovenly or lacking self-control:

"Oprah."

"Now, this is a woman who has every resource known to mankind at her disposal," Watman said. And yet, "she’s not winning the battle against the disease of obesity. Does that make her any of the [negative] things that people think about? No, it does not."

With two-thirds of Americans now considered overweight, you might think the bias would diminish. But in fact, surveys suggest it is on the rise.

(Courtesy of the Rudd Center for Food Policy and Obesity at Yale University)

Researchers have not just documented the extent of body-weight bias; they've also looked at the argument that negative attitudes towards obese people can be helpful, because they add incentive to lose weight.

They've found the opposite. In a study that came out this summer, experiencing weight-based discrimination made obese people three times likelier to stay that way.

As Rep. Rushing says, such research seems to be affecting the political climate — that helps explain the 7-to-1 vote by the Massachusetts legislature's Labor and Workforce Development Committee in early October.

Keiko Orrall, a Republican from Lakeville, Mass., was the lone vote against it; another member expressed concern about whether weight gain could keep employees from performing their work, the State House News Service reported.

No one was arguing that bias is acceptable. But Orrall says the focus needs to be on helping employers expand jobs, and adding new "protected classes" of employees could add to their fears of lawsuits, which can inhibit hiring.

"I understand the complexities of dealing with people of all different shapes and sizes, smokers and non-smokers, obese and very thin," she said. "You could likewise make the argument for anorexics and whether or not that’s going to be a health cost, an additional health cost. And so mostly, we need to give employers the freedom to employ those whom they think will benefit their company and will be able to do the work that they’re wanting them to do, and that’s where the focus needs to be."

When similar anti-discrimination bills have come up in other states, business groups have often opposed them, warning that they could bring a barrage of lawsuits, and arguing, like Keiko Orrall, that employers need a free hand in hiring and firing. Some also raise concerns that obese employees will incur higher health costs.

Michigan is the only state to have passed one of the bills --- a full 25 years ago — but several cities have passed similar measures in recent years, including Washington DC, San Francisco and Madison, Wisconsin.