(Reuters) Speculation that New Jersey Governor Chris Christie will enter the presidential race has led to a feverish debate about the possibility of having the fattest man in the White House since the corpulent William Howard Taft squeezed behind the big desk in the Oval Office.

Of course Taft, who reportedly weighed nearly 340 pounds during his presidency, ran for the highest office in 1908 when there wasn't the same focus on image and no need to worry about how a candidate looked on television.

Christie, who had ruled it out for months has been reconsidering whether to join the race for the Republican nomination in the past week, according to news reports.

He talks about his battle to lose weight and sometimes jokes about his size - he once exaggerated that he was 550 pounds. But he has not disclosed his actual weight.

That hasn't stopped an onslaught from television comedians and newspaper columnists in the past week.

Late-night talk-show host David Letterman's list of ten "ways the country would be different if Chris Christie was President" last Tuesday were all based on weight and food, including that the Cabinet would have a Secretary of Cake and the U.S. would invade pancake chain IHOP rather than Iraq.

But the jokes are no laughing matter to many.

The idea that poking such fun at Christie's weight is somehow acceptable in a way that it would not be if the jokes involved a disability or someone's ethnicity, adds to concerns about discrimination faced by the overweight.

In the New York Times on Sunday, columnist Frank Bruni attacked those who would dismiss Christie as a viable candidate because of his weight.

"Downgrade Christie for his truculent style. Reject him for his limited experience. But don't dwell on his heft. Girth doesn't equal character," wrote the former restaurant critic, who argued he would prefer "a big fat president" to a vain one who was always getting a make-up touch up.

With more than a third of Americans classified as obese, the topic is no laughing matter given the serious health issues associated with the condition, such as diabetes, heart disease and sleeping and breathing problems.

Any Christie presidential run will inevitably raise serious concerns about whether his heft could adversely affect his health and therefore his ability to serve as president.

"In general, the higher the body mass index the more likely a person is going to have significant obesity related conditions. And the longer you have the obesity, you have the cumulative effect on the organs," said Dr. Philip Schauer, director of the Bariatric and Metabolic Institute at the Cleveland Clinic, the nation's top-rated cardiac care hospital.

Body mass index, or BMI, is a measure of a person's weight related to their height. The 49-year-old Christie is about 5-foot-11.

FIT AND FAT?

"The human body was just not built to handle an extra 100, 150 pounds," Schauer said.

However, Schauer cautioned that not all obese patients are the same and genetics can play as big a role as body mass in whether someone suffers heart problems or other illnesses.

"While it may be more likely that someone of (Christie's) size has sleep apnea or may have certain joint issues, every person is different," agreed Dr Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York.

"People who have been active their whole life often mitigate against a lot of the risks. It's less likely to find fit fat people, but it's not impossible either. The largest patients I have are not diabetic," Roslin said.

"Christie's weight would be far more treatable than if John McCain had a recurrence of his melanoma," Roslin said, referring to the losing Republican candidate in the last presidential election.

"Should he get or have medical problems from his obesity that become difficult for him to carry on his daily activities there are some great options for him that are much more easily treatable than a lot of other conditions," said Roslin, citing bariatric surgery and gastric bypass procedures.

Christie, who suffers from asthma, was rushed to the hospital in July with breathing problems. Should he run for president in 2012, there will surely be demands for his health records as there were for McCain in 2008.

Doctors said Christie's asthma could well be related to his weight, though they also noted that presidents tend to have the best health care available.

A spokesman for Christie did not return calls seeking comment about the weight debate.

Past presidents, such as Franklin Roosevelt and John Kennedy, suffered from serious physical ailments that were largely kept from the public to keep them from seeming frail.

Other than staying away from horizontal stripes, it's a whole lot harder to hide obesity in a life spent in front of television cameras. Christie, who has admitted to struggling with his weight and overeating for years, will inevitably have to deal with the issue.

"It's as relevant to the political campaign as Obama's smoking was. I would hope that Christie's obesity is no more or less of an issue," Roslin said.

The stigma of obesity could ultimately prove more of a roadblock to presidential aspirations than any health issues caused by Christie's weight.

"There are stereotypes that are unfounded that relate to issues like laziness or inability to control themselves that can be very detrimental to individuals in terms of ability to get a good job, maintain a job," Schauer said.

"Someone running for office may have some of the same barriers," he said. "This health problem affects all Americans, all socioeconomic and ethnic groups. It is not a condition of poor uneducated people."

Roslin said the prejudice against the obese tends to be far worse for women and therefore less likely to impact Christie.

"If men are successful and seem athletic it mitigates the prejudice of obesity and that's just not true for women," he said.

Yet even though Americans were able to set aside centuries of prejudice to elect the first black president in 2008, the blogosphere is filled with people saying Christie is just too fat to be elected to the top office.

Still, opponents may be wary of using the weight issue against him after former New Jersey Governor Jon Corzine's attempts to mock Christie's girth failed in their 2009 election battle. Playing off allegations that Christie can be something of a bully, Corzine ads talked about him "throwing his weight around" as the phrase was juxtaposed with unflattering shots that exaggerated Christie's midsection and lumbering movement.

A seriously overweight president certainly shouldn't be remarkable given the ever-widening nature of the American population.

"Two thirds of Americans have a weight problem and about a third are obese," Schauer said. "So if you believe the notion that the president should represent the population, isn't it interesting that in the last three or four decades, when obesity has become so abundant, that we haven't really had a president that fits that category."