Vanessa Hudgens' sexy body makeover: What's the secret?

(CBS) Vanessa Hudgens says she junked the junk food, and it shows.

The 22-year-old actress - best known for her role on "High School Musical" - is flaunting her newly toned bikini body on a magazine cover and telling everyone what she gave up in order to get it.

First on her to-don't list: Junk food.

"I was so unhealthy," she says of her former adolescent self in the April issue of Shape magazine. "I used to go to Cold Stone Creamery, get a tub of Butterfinger ice cream, and eat it all before bedtime. And my fingers were permanently stained orange from Cheetos."

Now she eats healthier fare, starting with egg white omelets or oatmeal for breakfast. For lunch and dinner, she says, her favorite meal is now spinach salad with grilled chicken or salmon, almonds, feta cheese, truffle oil, and a sprinkle of "pure Himalayan" sea salt.

"When you're putting good stuff into your body, you feel so much better," she says.

Of course, eating right also reduces the risk of obesity and the health problems it brings, including heart disease, diabetes, and high blood pressure. Nearly 30 percent of children and teenagers in the U.S. are overweight or at risk of becoming overweight, according to the website of the U.S. Surgeon General. And overweight adolescents have a 70-percent risk of becoming overweight adults.

To go along with her new eating plan, Hudgens works out regularly, mixing up gym routines with Pilates, yoga, and spinning. And rather than going it alone, she works out alongside friends and family members.

"Having someone to go to classes with makes you want to do your best," she says, "not just for yourself but for the other person too."