"I enjoyed my time on the Biggest Loser ranch," Kournikova said in a statement to The Hollywood Reporter, who was first to report the exit. "Although I will not be returning as a full-time trainer on Season 13, I will always be a part of The Biggest Loser family and my commitment to bettering lives through health and fitness will continue."
NBC didn't immediately respond to TVGuide.com's request for comment.
The 30-year-old tennis pro joined the NBC weight-loss show along with Dolvett Quince to fill the void when trainer Jillian Michaels exited after Season 11. Before the full-time gig, she visited the ranch to lead a tennis-themed challenge in Season 10.