New Jersey Gov. Chris Christie is staying out of the Republican presidential race, but his brief flirtation sparked a debate that resonated in a country worried about the personal and national consequences of obesity: Does being overweight say anything about a person’s fitness for high office?

In his press conference Tuesday, Christie made clear he was rebuffing requests to enter the race because he was not ready to leave his job as governor. But he addressed the obesity issue, too.

“To say that because you’re overweight you are therefore undisciplined — you know, I don’t think undisciplined people get to achieve great positions in our society,” he said in answer to a reporter’s question.

He said he didn’t mind comedians joking about his size as long as they’re funny. But some of the columnists who’ve opined on the subject in recent days “are among the most ignorant people I’ve ever heard in my life.” Those who suggest that obesity may reveal character “further stigmatize people in a way that is really irrelevant,” he said. “Those are the people that we should really, you know, look down upon.”

It was the kind of tell-it-like-it-is moment that’s made the 49-year-old governor popular in New Jersey and elsewhere. But it will take more than a verbal smackdown to change the attitudes of lots of Americans.

“Public attitudes about obesity have been pretty negative for a while and don’t seem to be growing much better,” said Kelly Brownell, a psychologist heads the Rudd Center for Food Policy & Obesity at Yale University, who was interviewed in the days before Christie made his decision. “They are lazy, they are dirty, they are unintelligent, they lack willpower. These attitudes are very pervasive.”

He argues that blaming the individual is misplaced, given how difficult it is to maintain a healthy weight in modern America. He attributes the negative attitudes to traditional American values.

“Part of it is the American philosophy of personal responsibility and individual blame when things don’t go well,” Brownell said. “So people often get blamed for diseases that are not under their control, people are blamed for their poverty, people are blamed for their lack of education — things like that. Obesity gets especially stigmatized because it’s visible and because the social norms now are preoccupied with thinness.”

Earlier this week, the Obesity Society, which represents obesity researchers, came to Christie’s defense.

“Caution should be taken in making assumptions about a person’s lifestyle behaviors based on physical appearance alone. Individuals who are not struggling with their weight are not necessarily healthy,” the organization said in a statement. “A lean body does not reveal whether or not a person smokes cigarettes, drinks excessive alcohol, eats a balanced diet, exercises regularly or wears a seat belt. To single out a political candidate on the basis of body weight is discriminatory.”

The rate at which overweight people report experiencing discrimination, however, appears to be increasing, according to Rebecca M. Puhl, director of research at Yale’s center. In the past decade, the fraction of the population reporting discrimination based on weight increased from 7 percent to about 12 percent.

“We know weight-based discrimination occurs in many different settings,” Puhl said. “We see it in employment, in health-care facilities, in educational institutions. It’s a really socially acceptable form of bias.”

Some research hints that being overweight may not necessarily negatively affect men running for public office.

In a 2010 study published in the journal Obesity, Beth J. Miller and Jennifer D. Lungren of the University of Missouri-Kansas City conducted a detailed analysis of attitudes of 120 college students to hypothetical male and female obese and thin candidates.

Obese female candidates appeared to be judged more negatively than thin female candidates. That was not the case for males. In fact, obese male candidates appeared to be judged more positively than thin male candidates, the researchers found.

“Our suspicion is that societal/media pressures differ for men and women. There is much pressure on women to be thin and when women vary from the ‘thin ideal’ they are evaluated more negatively,” Miller wrote in an e-mail message. “For men, however, we believe the ideal is to have more muscle mass and be larger. As a result, images of obese men may be more in line with male muscular ideals.”

Christie has been candid about his own weight problem, saying he started putting on pounds after high school when he stopped playing organized sports and has tried dozens of diets over the years with varying success.

“It’s not something that . . . bothers me,” he told reporters Tuesday. “I’m not self-conscious about it. I’m self-aware. And you know, it is what it is.”

Christie suffers from asthma, which can be exacerbated by obesity, and was forced to seek hospital care in July when he had a severe attack that failed to respond to his inhaler. But he has not reported any other health problems related to his girth.

He hasn’t revealed his current weight. Where he falls on the weight and risk spectrum isn’t known.

He is reportedly 5 feet 11 inches. If he weighs 200 pounds, his “body mass index” (BMI) would be 27.9 and fall in the “overweight” range (25 to 29.9). If he weighs 225 pounds, his BMI would be 31.4, in the “obese” range (30 and above). If he weighs 260 pounds, it would be 36.3, into a category known as Class 2 obesity.

A debate rages in some quarters about whether the dangers of being overweight have been exaggerated. Some researchers argue that many people who are technically considered “overweight” or “obese” based on their weight might face little or no increased risk if they are physically fit. There is evidence that people in the low end of the “overweight” BMI range have slightly lower mortality than people of “normal” weight (BMI 18.5 to 24.9) .

But for most authorities there’s no doubt that being obese carries real hazards.

“It’s quite clear that obesity is not good for your overall health. It’s clearly associated with lots of different health conditions, and higher mortality,” said Lawrence H. Kushi, an epidemiologist and obesity expert at Kaiser Permanente, in Oakland, Calif.

Obesity increases the risk of heart attack, stroke, diabetes and certain cancers (colon, breast and kidney cancer among them). It doubles the risk of physical disability. It slightly raises the risk of mood and anxiety disorders, but appears to lower the risk of suicide. Overall, a non-smoking obese man in his 50s has about a 60 percent higher risk of dying than a similar man of normal weight.

A subset of obese people are even more likely to have problems — those with large waist size.

A study published last year by epidemiologists at the American Cancer Society found that an obese man whose waist size is over 47 inches has a twofold higher mortality risk than an obese man with a waist under 35 inches. It appears that fat under the abdominal muscles — so-called “visceral” fat — creates a low-grade state of inflammation that can have particularly bad effects.

“It’s good to watch your waist as well as your weight,” said Eric J. Jacobs, who led the study.

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Research editor Alice Crites contributed to this report.