Amber Riley is singing the joys of weight loss -- after she dropped 2 dress sizes!

The "Glee" star looked thinner than usual on the red carpet at this year's NAACP Image Awards, with the 26-year-old crediting a change in diet for the change.

"I decided I was going to make a change and eat healthier," Riley tells PEOPLE, adding that she stopped eating all the fast food that was "attacking my stomach."

It's not just her own red carpet looks that are getting an overhaul thanks to her slimmer physique -- her "Glee" character Mercedes' wardrobe has changed too.

"We had to revamp the wardrobe," she says. "They bought a lot of new clothes for me and we have to take in a lot of my pants and dresses."

Check out more celeb weight loss Before & Afters above!

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