In the ongoing war over America's waistline, the doctor's office is a front-line battleground, and the stakes couldn't be clearer.

Climbing obesity rates fuel related illnesses like type 2 diabetes and high blood pressure. Bariatric surgery, a drastic measure typically for the middle-aged, is becoming more routine for extremely obese adolescents. Obesity-related absences among U.S. employees cost the country as much as $6.38 billion annually in productivity, and scientists say severe weight gain is contributing to shrinking U.S. lifespans .

It's no wonder doctors, nurses and other primary caregivers often insist – sometimes frankly – that patients measured with a high body mass index must lose weight.

Yet an insurgency to the white-coat offensive is rising.

Encapsulated by an essayist with the nom de guerre Your Fat Friend, overweight people are pushing back against caregivers who they say fat-shame them and blame common medical problems on their weight. Obesity, they say, isn't always the cause of their issues, and diet and exercise aren't always the solution.

The stigma she and other overweight people face too often "is thinly veiled by a purported 'concern for our health,'" amounting to "well-intended bullying that only ends up compounding the harms we face," Your Fat Friend wrote in an unflinching essay in December, one in a series arguing against size discrimination. "If so many are, as they claim, 'just concerned about fat people's health,' the best way to express that concern is to address the overwhelming stigma facing fat people in doctor's offices."

There's little doubt that the debate over obesity, fat acceptance and health has entered the national conversation.

The body-positivity movement , once on the fringe, has gone mainstream. After years of slender-only models, New York Fashion Week saw a substantial number of "plus-size" women strutting down the runway. Chrissy Metz, a young actress who has struggled with weight issues, has a lead role in the hit NBC drama "This Is Us," playing a character coming to terms with her oversized body. On ABC, the comedy "American Housewife" stars Katie Mixon as the plus-size, tart-tongued title character. "Shrill: Notes From a Loud Woman" – Lindy West's best-selling memoir on life as an overweight woman – is now a successful Hulu TV series.

But not everyone is on the body-positive bandwagon.

Facing a withering backlash, fitness guru Jillian Michaels said she shouldn't have name-checked Lizzo – an unapologetically thick, Grammy-winning hip-hop sensation who promotes body positivity – as a woman at risk for ill health. But Michaels, a gung-ho trainer on the competitive weight-loss reality show "The Biggest Loser," also has held her ground about the dangers of excess body fat.

Meanwhile, pop singer Adele, once known for embracing her plus-size image, recently dropped some 100 pounds and literally embodied the issue: While fans have cheered her dramatic transformation, critics contend doing so is simply another form of fat-shaming .

Less visible than obese TV stars and celebrity-fueled Twitter beefs, however, are the everyday struggles severely overweight people like Your Fat Friend – a Californian who's 5 feet 10 inches tall and "around 330 pounds," she says – face when they go to the doctor.

Much like callous strangers who make unkind remarks to her face, insensitive doctors and nurses often feel free to tease or scold her about her weight, Your Fat Friend told U.S. News in a recent interview. Some caregivers, she says, treat her differently, refusing to order a routine medical test because she's too heavy or blaming ailments from an earache to internal bleeding on her weight.

"There is no doubt that, particularly for the heaviest 5 percent or so, there is a health cost," like diabetes or heart disease, says Your Fat Friend, an alias to protect against online trolling ("I've frequently received threats of violence," she says). But, she adds, "there's also a growing body of research that indicates that the health risks we typically associate with being fat may be driven by fat people's experiences of bias and discrimination."

After enduring one grueling weight-loss program after another for most of her life, including attending Weight Watchers meetings at age 11, YFF has accepted it as fact: Starvation diets and punishing workouts will never make her thin.

She spent years of her life "dieting, exercising, even developing a restrictive eating disorder, and nothing changed my size," says YFF, who wears a women's size 26. "I'd lose 10 or 20 pounds – sometimes as much as 50 pounds – but it always came back, often even when I stayed on those diets. Even when I lost more significant amounts of weight, I was still fat, and still faced a whole lot of bias."

Now, at age 36, she says her vital signs – including blood pressure and blood sugar – are normal, she eats a balanced diet and is a regular at the gym.

Medical researchers and obesity-medicine specialists say YFF has a point.

Research indicates many factors – from genetics to environment – are tied to obesity, and people who lose weight often gain it back. Study after study also confirms negative stereotypes about fat people are pervasive within the medical community.

"We know from research that weight bias is common in physicians and other health care providers," says Rebecca Puhl, deputy director of the University of Connecticut Rudd Center for Food Policy & Obesity. "In fact, research shows that these biases are as common among medical professionals and doctors as they are in the general population."

In 2018, the AMA Journal of Ethics published research measuring the problem among first-year medical school students. It found that 70% of students held a "thin preference," while most students thought obesity is a disease (89%) or a behavioral problem (88%). About three-quarters of students surveyed believed that obesity is the result of ignorance, and 28% considered obese people lazy.

Another oft-referenced survey published in 2003 showed that, among primary care doctors, more than 50% reported viewing obese patients as awkward, unattractive, ugly, and noncompliant .

The hurtful stereotypes may make sick people even sicker.

Patients "notice these negative attitudes, describing that they receive derogatory comments from health professionals," a 2013 study of medical students notes . A negative feedback loop ensues, "(contributing) to obese individuals avoiding public exercise and seeking fewer preventive medicine services."

Dr. Fatima Cody Stanford, an assistant professor at Harvard Medical School and an obesity specialist at Massachusetts General Hospital, says negative attitudes and stereotypes about overweight people are a more widespread problem than racism.

"The biggest form of bias now present in the United States is weight bias, and shaming people if they carry excess weight," Stanford says. "Weight bias has surpassed race bias. It is indeed OK if you go on TV and make fun of people because of their weight."

Frequently, new patients "come at me in a defensive mode," she says. When they notice her lack of judgment, she says, "you see them let their guard down and they start crying. Something that a doctor once told them made them feel unworthy."

"I usually go through a box of Kleenex every two patient days."

Yet some physicians – and some fat people themselves – question the body-acceptance trend, and suggest embracing it within the medical community will have unintended, potentially dangerous consequences.

In a 2018 New York Times essay, Kelly deVos, an advocate of body positivity and author of the young-adult novel "Fat Girl on a Plane," wrote about having an eye-opening weight-loss conversation with her daughter. Later, hospitalized for an infected spider bite, deVos – who said she's weighed 300 pounds – found out she was diabetic.

Despite being a self-proclaimed "fat woman," deVos balked at the diagnosis: She exercised and ate healthy food. "How can I have type 2 diabetes?" she asked her doctor.

His answer, she wrote, was brutally frank: 'Look at where you are,'" he snapped. "'You're not healthy at any size.'"

"The problem with today's version of body positivity is that it refuses to acknowledge that no one approach is right for every person. … I was the 'wrong' kind of body positive because I'd been forced to admit that there could be serious health consequences to fatness," she wrote. Since then, "I've come to feel that loving yourself and desiring to change yourself are two sentiments that should be able to peacefully coexist."

Dr. Jenny Hartsock-Vandine, a hospitalist and family medicine practitioner, wrote on the medical blog KevinMD in 2018 that unconditional acceptance of an oversized body equates to normalizing obesity. Her reasoning is deeply personal: Hartsock-Vandine has fought obesity herself.

"As a physician and as someone who has been obese or morbidly obese my adult life, I know first hand what it's like to hate my body and feel ashamed of it," wrote Hartsock-Vandine, who practices in Oregon and kept pull-no-punches video blogs tracking her progress from 275 pounds to a healthier body size. "I still do this very moment as I type this, that's something I have to work on."

"Funny thing is, I am much more understanding of my obese patients than of myself, and I think my own struggles make me more empathetic," she continued, emphasizing that fat-shaming among doctors is a real issue that must be addressed. "There is a place in which you can encourage people to lose weight without being cruel and judgmental.

Dr. Jamie Coleman – a trauma surgeon at Denver Health and an essayist on health – agrees.

It's wrong for doctors to discriminate against or bully people with obesity. But, she says, caregivers still must put a hard truth on the table: Being overweight is a clear health hazard, and losing weight is the best option.

Excess body weight is "a contributing factor in hundreds of thousands of deaths each year and is associated with a shorter life expectancy," says Coleman, who adds that excess weight also causes problems in the operating room. "Obesity puts patients at risk not only for hypertension and diabetes, but also strokes, sleep apnea, fatty liver, kidney disease and several forms of cancer."

That's the reason health guidelines strongly recommend "not only having a balanced diet and an active lifestyle" but also "maintaining a healthy BMI," or body mass index, she says.

Far easier said than done, says Your Fat Friend. Enduring the stress and denial of hardcore diets to reach a healthy BMI – even when, she says, she's healthy at her present weight by most measurements and has good eating and exercise habits – is counterproductive, she says.

"Part of the question, for me, has got to do with the quality of life and the amount of suffering that fat people have to experience," particularly at the doctor's office, she says. "The mental health cost of stigma discrimination and self-loathing is so high that the quality of life is really diminished."

But both Coleman, the trauma surgeon, and Hartsock-Vandine, the physician who tracked her own weight loss, argue it's not an either-or situation. Both have compared treating overweight patients to caring for a smoker or drug user: Accepting the problem won't make the risks go away.

"Unlike talking to a patient who ... may not know they have high cholesterol, every patient who is obese likely already knows they are at an unhealthy weight," Coleman says. "This again reinforces that doctors shouldn't inform their patients they are at an unhealthy weight, they should have a discussion with their patients about how their weight is impacting their health and help their patients gain the knowledge and strategies they need to obtain a healthy weight."

Stanford, the obesity specialist, notes a small but growing number of medical schools are including curriculums to teach doctors how to approach obesity with empathy and respect, but that more education needs to happen to overturn biases.

Coleman agrees that respect is key, but says the bottom line is the inescapable truth: Obesity is a clear health risk, and caregivers must address it with their patients.