"No one likes to be not toned when you are dating someone," the Duets star says

By Jessica Herndon
Updated May 23, 2012 03:00 PM
Kevin Winter/Getty; Inset: Courtesy Brandon Blackstock

He may have limited some of her songwriting subjects – especially those angry, brokenhearted ones – but Kelly Clarkson says her boyfriend has fueled her desire to work out.

“I would love to say that it had something to do with my work, but it doesn’t,” Clarkson, 30, whose new singing competition Duets premieres Thursday, told reporters during a conference call. “I have a boyfriend, and if I’m being completely honest, no one likes to be not toned when you are dating someone.”

Having revved up her workout routine and by restricting her diet, Clarkson says the pounds have come off.

“I’m eating better and working out, but I’ve always fluctuated within 20 lbs.,” she adds. “My whole life I’ve been like that.”

Sharing a trainer with her talent manager beau Brandon Blackstock (the son of Clarkson’s manager of five years, and the stepson of Reba), 35, offers added incentive.

“I tone whenever I want, and I chose to now because my boyfriend and I are both really into it,” she says. “But we don’t work out together.”

“We did that once and I didn’t like huffing and puffing,” she continues. “I didn’t like looking all red and gross, so I don’t do that.”

But it’s not just the gym they have in common.

“We both love music so we go to shows together,” Clarkson says. “I am just more active with him.”