Kevin Federline's ponderous girth appears to have caught up with him.

In his defense, the only reason he wilted in the Western Australia heat this week is that he's doing something about it - the former spouse of Britney Spears is filming Excess Baggage, the Aussie version of Celebrity Fit Club.

In any case, dude passed out down under. He's not small.

This man was once married to Britney Spears. Amazing.

A show rep says the season's first shoot was in late November in the Kimberley region in Outback Western Australia, which is "widely regarded as one of the most remote and altogether hostile parts of the country," and things got heated.

Literally.

During the shoot, under advice from the show's medic, Kevin Federline, who just became a dad for the fifth time, was "taken to hospital with signs of heat stress."

However, K-Fed resumed filming in the same location shortly after and is currently continuing with the show, which will air on the Nine Network next year.