From his Oscar acceptance speech to his transcontinental jaunts to lecture about the dangers of global warming, Al Gore is back. A man whose endorsement was deemed toxic during the last presidential campaign (Howard Dean received the blessing), he has reemerged as part of the popular conversation, a man to take seriously.

Yes, we've certainly seen a lot of Al Gore lately. And there's a lot of Al Gore to see. Calling Planet Girth!

There seems to be no quenching the speculation that he still yearns to be president. But how can we tell for sure? To hear some pundits tell it, we'll know when he goes on a diet.

"Al Gore is thinking seriously about [running]," former CBS anchor Dan Rather said recently on "The Chris Matthews Show." "He's beginning to lose weight--"

"I hear he's made a commitment to a friend for a crash course to lose 40 pounds right away," Matthews said, interrupting (of course).

"Well," Rather said, "the prosecution rests, your honor."

Gore's 2000 campaign chairman, Donna Brazile said, while speaking to students at Moravian College in January, that she foresaw a campaign announcement if he dropped 25 to 30 pounds for his Oscar night debut.

Whether Gore runs or not, the attention paid to his waistline brings up a larger question: Why can't a fat person be president? Examine the current field of contenders in both parties. They may not all be as svelte as Barack Obama, but not a single one could fairly be described as corpulent. Is avoirdupois the final taboo?

Looking for answers, we first turned to Men's Health Editor in Chief David Zinczenko, whose ungodly good looks have made him a morning-show regular and a walking billboard for his magazine. Zinczenko, in a Discovery Channel-like explanation, said, "In a tribe, they gauge the alpha male's dominance by physical prowess. We're not that removed from our animal selves.

"Physical fitness, and especially aerobic fitness, are tightly tied with intelligence," the abs guru continued. "There are studies that show a direct link between fitness and mental energy, fitness and efficiency, fitness and leadership. The physical manifestation impresses others because they know that a fit man is a sharper man."

Still, there is some precedent for a president who couldn't pass the President's Physical Fitness Test. Namely, William Howard Taft (1909-1913), the only man to serve as both commander in chief and Supreme Court chief justice. During Taft's tenure, he's said to have weighed around 300 pounds.

Of course that was before television, before the dreamy-looking John F. Kennedy (who tightly guarded his own physical maladies), and long before then-Arkansas Gov. Mike Huckabee lost 105 pounds in 10 months and used it as a springboard for his current presidential run. Bill Clinton had his modest pudge -- although, according to his former lead strategist James Carville, "he had this McDonald's thing and he liked tamales, but I just don't recall us saying, 'We need him to knock off five or seven pounds.' "

Leaving image questions aside, there would be practical reasons for Gore -- who finished the 1997 Marine Corps Marathon in 4:58:25 and once penned a physical fitness column in a 2000 issue of Men's Health -- to lose that weight. Presidential campaigns are physically taxing, demanding long hours on the road and in the air. They require a candidate, at each event, to go all out, as Joe DiMaggio did, because, as he said, the person watching might be seeing him for the first time.

"Anybody that's been on the circuit knows how physically grueling it is," said Democratic Party strategist Steve Jarding. "They have exercise programs not to look good but to prepare for the rigors of the campaign trail."

"Everybody has to watch it," Carville said of campaigning. "It's all bad food on the run. It's like Al Gore releasing a movie, with all the receptions and galas. I saw him in Paris, and I'm sure they fed him pretty good over there."

Gore now almost seems a perfect counterweight to Obama and John Edwards. There are moments where one fears that if Obama were to lose any weight he'd be on the cover of Us Weekly with Lindsay Lohan. Enter, then, the Robust Gore, who, in Huckabee fashion, could shed those pounds as a sign of his devotion to a cause, the physical manifestation of someone who wanted something done and then went ahead and did it.

"Could Al Gore win the presidency at his current weight?" Carville said. "Yes, he could. But a lot of things have to fall into place for him. First, he's gotta run. That's kind of a requirement. . . .

"For a guy who people say needs to be humanized, there's nothing to make you more human like a diet. Nothing would make you more human than eating lettuce and vinegar for lunch. Everyone could relate to that.

"But let's be fair to Gore," Carville continued. "He's overweight, but knowing him and his wife, I wouldn't be surprised if he lost 15 pounds or so. And I think if people thought he could get us out of the mess we're in with Iraq, they wouldn't care how fat he is."