Jenny McCarthy poses for a photo during the 2009 Weight Watchers "Lose for Good" Campaign Kick-Off on August 12, 2009. Frank Micelotta/PictureGroupUs Magazine See before and after photos of celebrity weight winners.
In 2002, she joined her local Weight Watchers after having son Evan, now 7, and the size-4 star admits, "I still kind of count points in my head."
In fact, McCarthy, 36, is serving as ambassador for Weight Watchers' Lose for Good Campaign, which is helping people lose weight and raising money to fight hunger this fall.
The 5-foot-7, 125-pound star tells Us that nutrition is key to a healthy lifestyle.
See photos of other stars getting fit.
"Working out tightens you up and helps burn calories, but what you put in your mouth makes all the difference," she says.
After discovering she has 60 food allergies, McCarthy switched to a diet free of wheat, dairy and sugar (she also avoids meat for personal reasons) -- and fills up on fresh fruits and veggies.
One person heeding her advice is her beau of three years, Jim Carrey, 47. The actor has also sworn off wheat and dairy, and he takes an active role in cultivating natural ingredients.
See photos of incredible shrinking stars.
"We just planted our own organic garden in the backyard, and we love it!" McCarthy tells Us.
As for exercise, the actress does Bikram yoga twice a week and goes for 45-minute jogs twice a week.
"You have to keep up now," she jokes, "or be made fun of by Perez Hilton!"
For more of McCarthy's health and fitness tips, pick up the new issue of Us Weekly, on newsstands now.
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