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."