Britney Spears Reveals Which McDonald's Item She Can't Live Without

Britney Spears may be getting ready to go out on tour, but all the hard work has her craving one [...]

Britney Spears may be getting ready to go out on tour, but all the hard work has her craving one particular McDonald's offering.

The singer opened up to Entertainment Tonight about getting in shape for the North American and European legs of her upcoming Piece of Me Tour.

"This round of shows that we are doing on tour, they are back to back, so each show is like... I don't have time apart, besides flying," Spears said. "My show is a workout in itself. It really keeps you strong."

With not a lot of time to hit the gym on the road, Spears said she is working out hard before the kickoff date. Fans have been following her workouts as she posts plenty of videos on Instagram, including some with boyfriend Sam Asghari.

However, working out is not the only way Spears stays in shape. Those toned abs are made in the kitchen — with a little help from a certain fast food restaurant meal.

"Sometimes I'm just like, 'I want a hamburger!' but when I'm in work mode, I want [to eat] very clean. I want clean chicken and veggies that's it," she revealed. "My stomach is so sensitive, if I have a steak, I will be sick for three days."

"The burger is fine, but I have the small burgers from McDonald's. The happy meal!" she added.

The "Toxic" singer is getting ready to perform 30 shows in just 51 days, with many concerts already sold out. Along the way, she will have 12-year-old Sean Preston and 11-year-old Jayden James going on tour with her to cheer her on.

"They will come with me. They enjoy it," she shared, confessing that Sean and Jayden actually have a little bit of influence over her set list.

"My kids, they have been putting new remixes into my show and stuff... there is one of the new songs on the radio, and [my son is] like, 'Mom, that is so cool!'" Spears revealed. "So I'm putting all these different new songs in my show, so they are coming along."

Jayden and Preston's attendance on tour comes as Spears and ex-husband and baby daddy Kevin Federline continue their ongoing legal battle over child support for the kids.

When Spears and Federline initially divorced in 2007, a settlement was made where Spears would cut her ex-husband a $20,000 check monthly for child support, based on how much she was making at that time. However reports of Federline approaching Spears and her legal team about renegotiating that deal for more money began to appear in February.

Despite the legal drama, Spears seems to be in good spirits and ready to take her Piece of Me tour to the next level.

Spears' Piece of Me Tour kicks off July 12 at Maryland's MGM National Harbor.