You might think that’s because it would be too dangerous to go there, mentioning a female politician’s weight. No, although that’s true, too.

Rather, we wouldn’t be having this discussion because corpulent Christine Christie, if you can imagine her, probably wouldn’t have been elected governor of New Jersey in the first place. Party leaders and wealthy donors certainly wouldn’t be beseeching her to run for president.

Appearance matters in politics, for male and female candidates. But it is an inescapable fact of political life that for female candidates, appearance matters more. Successful female politicians needn’t be model-thin, but cringe-at-the-thought-of-sitting-next-to-them-on-an-airplane levels of obesity are rare among women in politics. In a potential presidential candidate, being as fat as Christie would be unimaginable for a woman.

It is no accident — although it is bad political manners to mention it — that the two most prominent women in the Republican party today, Sarah Palin and Michele Bachmann, are trim and attractive.

Christie’s weight is no doubt unwanted political baggage. After all, former Arkansas Gov. Mike Huckabee lost more than 100 pounds before his presidential race. Mississippi Gov. Haley Barbour, when he was, sorry, weighing a presidential campaign, joked that people would know he was running if he lost 40 pounds.

But those examples also demonstrate a certain comfort level among male politicians with their extra poundage. There is an Everyman aspect to a pudgy male pol. He can lament his weight without being humiliated by it.

Christie’s obesity offers a regular-guy contrast to Mitt Romney’s chiseled chin and perfect hair. “I weigh too much because I eat too much,” he confessed after being treated for an asthma attack this summer. “And I eat some bad things too.” Who can’t identify with that?

It is hard to imagine a female politician talking about her weight with that degree of equanimity. When Vogue interviewed Kirsten Gillibrand after the New York senator lost weight, she initially demurred about saying exactly how much. “Can I tell you off the record?” she asked the Vogue writer, before eventually allowing that she had dropped 40 pounds.

Gillibrand’s Missouri colleague, Sen. Claire McCaskill, bravely took to Twitter to embarrass herself into losing weight. “I’m tired of looking and feeling fat,” she tweeted in May. “Maybe talking about it publicly will keep me on track as I try to be more disciplined.”

And then-Sen. Hillary Clinton, at a forum on faith during the 2008 presidential campaign, told how she sometimes sought divine intervention. “Sometimes I say, ‘Oh Lord, why can’t you help me lose weight?’ ” Clinton confided.

None of these women are close to Christie-esque proportions.

Sure, Christie’s weight will be a topic if he decides to run. If he were a woman, though, it would have been the end of the discussion. That’s not a complaint, just a simple observation of reality when it comes to gender politics.