Yearwood, 48, is the wife of country music star Garth Brooks. She also headlines the Food Network program "Trisha's Southern Kitchen."
The recording artist turned heads at Sunday's ACMs when she showed off her smaller waistline in a stunning red Stella McCartney gown.
She confirmed to People.com she has lost "about 20 pounds" by eating "very little sugar."
"Real people battle their weight," she said. "We all struggled between eating healthy and falling off the wagon. That's how I live."
Her representative told E! News Yearwood also has been focusing on exercise to maintain her shape.
"Trisha has always been a successful, shapely bombshell. Recently she has taken her fitness routine to a new level," the publicist said.
"One of the ways she has done that is by mixing it up and making exercising fun. As the host of 'Trisha's Southern Kitchen,' she still makes her traditional recipes like mac and cheese and country quiche, but those dishes are balanced with the moderation she has always spoken about."