When the American Medical Association declared obesity a disease this week, Ragen Chastain, a ballroom dancer, writer, public speaker and self-described “fat person.” was offended.

“Against their own recommendations, the AMA declared body size – including my body size – to be a disease,” she wrote on her blog, “Dances With Fat.”

Chastain is tired of many medical professionals -- and society as a whole -- assuming that everyone who is overweight or obese is unhealthy, lazy or diseased. There are plenty of people like her, Chastain says, who are overweight but who are also active, eat well and take care of themselves, and they see no need to apologize for their weight.

Weight and health are two separate things, Chastain firmly believes, and it makes no more sense to assume that an overweight person is not physically fit as to assume a thin person is in great shape.

“It makes no sense to focus on a body size as an indicator of health. There are people of every body size with different kinds of health,” she told CTVNews.ca, speaking from Los Angeles.

Chastain says she stopped worrying about the numbers on the scale years ago. She now focuses on a concept known as “Health at Every Size,” or HAES (pronounced “hase.”) Instead of concentrating on her size, she maintains healthy habits such as eating right and exercising to keep her blood pressure healthy, her cholesterol and glucose levels low and to increase her strength, stamina and flexibility.

Chastain says she knows she’s in good shape and feels great.

“If I were a thin person and I walked into a doctor’s office, they’d say ‘You’re in excellent health’,” she says.

Indeed, there is a growing body of research that backs up the HAES philosophy.

A number of studies in recent years have revealed that obese people who are “metabolically healthy” -- meaning no problems with blood pressure, cholesterol and glucose management -- are at no greater risk of developing cardiovascular disease or cancer than normal weight people. Some studies have even found that overweight people tend to live longer than slim or underweight people.

One recent study by Canadian researchers, published in 2011, tracked 6,000 obese Americans and looked at their risk of dying over 16 years from heart disease, or other causes, compared with the risks for more than 23,000 normal-weight people.

They found that the people who were obese but otherwise healthy lived just as long as their lean counterparts. They were also less likely to die from cardiovascular causes over the study period as those who were obese and had health problems.

The researchers, led by York University health sciences professor Jennifer Kuk, said their study showed body weight alone cannot distinguish healthy and unhealthy obese individuals.

“Our findings challenge the idea that all obese individuals need to lose weight," Kuk said at the time.

Chastain says she has a family doctor who supports her HAES choices, but she says it’s clear from this week’s AMA decision that the medical community still paints all obese people with the same brush, regardless of their heart health.

“The government’s own language isn’t helping. I mean we have a ‘war on obesity’ right now. We are told: ‘if you look at fat people, you can tell they’re lazy and not athletic,’ ” she says. “Anytime you take a group of people and say you can identify them just by sight and talk about their cost on society, it’s a problem.”

Dr. Arya Sharma, a professor of medicine at the University of Alberta and the scientific director of the Canadian Obesity Network, has researched the management of obesity for more than a decade. He agrees that obese patients face plenty of discrimination in the medical system.

“Fat people are always told to lose weight, no matter what,” he says, speaking from his office in Edmonton.

“You could go to your doctor and say you have a headache, and they’ll tell you to lose weight. It’s become a reflex thing. Everyone automatically assumes if you’re big, every problem is because you’re big.”

Sharma also agrees that someone who is obese can still be metabolically healthy even if they’re outside the “normal weight” range.

“If you eat healthier and get more physically active, of course your diabetes is going to improve, even if you don’t lose weight. The same for hypertension. There are things you can improve without weight loss,” he says.

But Sharma cautions that “sooner or later, in most obese people, their weight will become a health problem.”

There are a number of health conditions that are associated with obesity and that are unrelated to cardiovascular health, he says -- conditions such as joint problems, skin fold infections, osteoarthritis, sleep apnea, even reflux disease.

“All those things that are what I call the ‘mechanical complications’ of obesity, the ones that are caused really just because you’re big,” he says.

“You can eat as healthy as you want, but you’re still going to have those problems. Fixing those actually does require weight loss.”

After struggling with an eating disorder and then trying countless diets for years, Chastain is done with focusing on losing weight. She notes that long-term studies show few people can maintain substantial weight loss for long anyway, and the vast majority of people regain their weight after five years -- including many who regain more than they initially lost.

She believes doctors should stop seeing body size as a diagnosis and focus instead on encouraging patients to adopt habits that lead to good health.

“I think the best idea is to remove weight from the conversation and focus completely on health so people aren’t stigmatized for their body size,” she says.

“Because the more you stigmatize somebody, the more they think their body is unworthy of care and the less they care for it. People won’t take care of things they hate.”