But damn if these celebrity dads don't look like they've been incubating for nine months.
Federline caught the eye of his ex-wife, Britney Spears, when he worked it out as the resident hunk of her backup dance crew. Now, his former six-pack abs have gone to flab, and the 31-year-old father of four can barely handle 18 holes of golf, let alone a sweaty stage routine.
According to Usmagazine.com, instead of traversing the greens at a recent celebrity golf tournament, Federline opted for an even lower-impact workout -- smoking cigarettes and sipping cocktails in the shade with girlfriend Victoria Prince.
"He used to be extremely active, but now he has all this money because of his ex-wife, and he doesn't have to pound the pavement anymore," said Natalie Thomas, Us Weekly magazine's deputy news editor. "There's a lot more alcohol involved and a lot less moving around."
Federline's been packing on the pounds for more than a year now. Last March, Shar Jackson, the woman he was engaged to pre-Britney and with whom he has two children, came to his defense, telling Usmagazine.com, "It's daddy weight! When you are a full-time parent, sometimes you can't focus on you."
Be that as it may, K-Fed may consider hopping on whatever plan Spears used to shape up for her world tour (if not to score the reality TV show he reportedly wants, then perhaps to set an example for his kids) and finding a workout buddy in a fellow chubby celebrity father. Below, the candidates:
The father of eight let loose since he and Kate Gosselin announced their split. Though the newly single Gosselin gravitates toward trendy T-shirts and 20-something girls, he seems to have simultaneously given up the gym, stretching those tight-fitting crewnecks a tad too thin, probably much to the chagrin of his gal pals.
It's a departure from his married days.
"Throughout 'Jon & Kate Plus 8,' Jon was adamant about working on his physique," Thomas said. "We saw him constantly going to the gym. He was trying hard to shed pounds and eat healthy. Now, he's out making the rounds at the bars."
Gosselin's weight gain probably began when his marriage started falling apart.
"With Jon, as the deterioration of the marriage became more evident, he became heavier and heavier," said MomLogic.com clinical psychologist Michelle Golland. "It could be a sign of depression."
But that hasn't earned Gosselin, who has ample time to exercise now that he's not running after a clan of eight 24/7, much sympathy.
"Gosselin, go up to 500 pounds, 600 pounds, 2,000 pounds," spat E! online columnist Ted Casablanca. "Eat until you explode. You're just such a hideous person anyway."
The one-time Batman and father of two now battles a villain far more menacing than The Riddler: frozen desserts.
"It's such a crime. He was so beautiful," Casablanca lamented. "These guys just get so exhausted playing the hunk, playing the he-man."
Indeed, Kilmer threw his pectorals to the wind when he packed on pounds to play a nihilistic prisoner in 2008's "Loner."
"He's given up. So I just started eating -- everyone else was working out and I was ordering the extra Haagen-Dazs," Kilmer told The New York Daily News in July '08. "But I would not have been this thorough if I had known how hard it would be to lose the weight -- it's harder after 40. And you've got to suffer the private photos of you getting ready. You can't go running after the paparazzi, saying, 'But it's for a movie! It's for a movie!'"
Lithe and limber in the 1970s, Travolta got down and dirty on the dance floor in "Saturday Night Fever." Today, more than three decades and two children later, it's doubtful he'd be able to squeeze into that signature white suit.
"John Travolta's always struggled with his weight," Casablanca said. "I don't think he can take the pressures of maintaining the life of a romantic lead off camera."
But if Travolta hasn't prioritized his cardio in the past few months, he can't be blamed. His 16-year-old son, Jett, died in January after suffering a seizure.
"He's probably still learning to cope with his son's death," Golland said. "In times of tragedy, people usually turn to comfort food, not the gym."
Those guns Crowe sported for "Gladiator"? Gone.
Since the Aussie actor won an Oscar for his role in the 2000 epic, he's fathered two sons and morphed from macho man to marshmallow man. But he's also shifted from films that require him to run around shirtless to suit-friendly fare, such as "American Gangster."
"He's a big guy -- a rugby player, a manly man," said Thomas. "I think he's happier when he gets to live how he wants, he loves a good beer and pub food. Now that he's a father, he's not vying for the hunky leading roles. He'll trim down for roles when it's time, but when it's not, he indulges."
Not that there's anything wrong with that. In image obsessed Hollywood, it's refreshing to run across people not tethered to the treadmill or wedded to wheatgrass. But, if any of these men want to enjoy long, lucrative careers, they might follow the examples set by their more-fit-than-fat elders.
"Look at Sean Connery, Warren Beatty, Michael Douglas -- they all still have excellent figures," Casablanca said. "You can maintain a nice figure into your autumn years. These guys can't blame it on age alone. They can get back in the game [Ed. and the gym] if they really want it."