Jenny McCarthy on Shape Magazine Credit: Shape/Nino Munoz

Jenny McCarthy is kicking off 2013 with a bang -- and a bangin' bod.

Now a 40-year-old single mom, the actress, comedian, model and author looks better than ever in the January-February issue of SHAPE magazine.

On the cover, the blonde, blue-eyed bombshell flashes her taut, seemingly fat-free abs, legs and toned arms in a tiny neon-green bikini as she peels off a clingy white, green and black tank top.

To maintain that flawless The former Playmate of the Year and mother to son Evan, 10, is admirably committed -- working out five days a week. McCarthy's go-to moves? "Lunges, sit ups and pushups -- because I'm kind of working my whole body," McCarthy explains to Shape in a behind-the-scenes video. "Planking is still an awesome exercise for the core and your arms."

The Singled Out host (who split with Chicago Beas linebacker Brian Urlacher in August) also has her own super-food: Watermelon.

"It helps you if you retain water," she explained of the "Natural diuretic . . . It's really filling and yummy."

Her ultimate stay-fit secret? "Besides the actual working out, food is the most important thing," she muses. "Especially in today's age how convenient fast food restaurants are, and how exhausted we are as mothers. It's too overwhelming that we sacrifice [healthy] food."