Jenny McCarthy covers the January-February issue of Shape magazine, and we can't believe how tight the 40-year-old star's abs are!

Of course, there's a lot of hard work behind her amazing body, as the former Playmate of the Year reveals that she works out five days a week and watches what she eats. On her gym routine, Jenny tells the mag, "[I do] lunges, sit ups and pushups -- because I'm kind of working my whole body. Planking is still an awesome exercise for the core and your arms."

"Besides the actual working out, food is the most important thing," she added. "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." So what's her fav snack? Watermelon! "It helps you if you retain water," she explained. "It's really filling and yummy."