Kevin Federline Kevin Federline

Kevin Federline says depression caused his very visible weight gain.

"Once you get depressed, you don't really feel like doing anything. You're kind of discouraged about yourself, and then the weight gain too — or that makes me more depressed," Federline tells Access Hollywood.

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The choreographer also pointed to his divorce from Britney Spears in 2006. "I'm not going to say [the divorce] was the total cause of it, but I mean, just not being happy with myself was probably the main part of my depression."

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But things are looking up for Federline, his ex-wife and their two sons. "It's gotten so much better from where we were," he says. "I'm in the best possible scenario right now. I'm really happy for her."

Federline will be next seen as a contestant on VH1's Celebrity Fit Club: Boot Camp (premieres Monday, Feb. 8 at 9/8c) alongside such celebrities as ex-girlfriend Shar Jackson, Nicole Eggert and Bobby Brown.