KFederlineEXPLODING0925.jpg As if Britney's alimony wasn't enough to keep Kevin Federline's fridge fully stocked, now he's adding even more cash to the pot!

X17online previously confirmed that K-Fed would appear on VH1's Celebrity Fit Club, and now MSNBC is reporting that Brit's chubby ex-hubby is getting paid $100,000 to lose the blubber!

But get this...K-Fed has reportedly been overeating to get ready for the show, and Us Weekly reports that as soon as he found out he was cast, “he started putting on even more weight on purpose." A source close to K-Fed says, "He thinks that if he goes on the show, loses a ton of weight, and seems really likeable, he’ll get more deals afterward. The way he sees it, he could have another show after Fit Club, and that would open the door to working on music again, maybe even a fashion line."

Riiight. But at least he's doing something about that baby bump beer belly of his!