FORT WORTH, Texas -- Kyle Larson smiled with a bottle of an electrolyte drink in his hand Thursday, showing no ill effects from a fainting spell that kept him out of the March 29 race at Martinsville Speedway.

Team owner Chip Ganassi told driver Kyle Larson to eat better after fainting and missing a race due to dehydration. Jared C. Tilton/NASCAR/Getty Images

About the only lingering effects from his March 28 fainting spell are texts from car owner Chip Ganassi on what to eat.

The 22-year-old Larson fainted following an autograph session March 28, a day before the Martinsville race, and was held out of the event so doctors could run tests to rule out any serious health issues. The tests came out negative and has doctors theorizing that he fainted from dehydration. He is set to practice Friday and race Sunday in the Duck Commander 500 at Texas Motor Speedway.

"That morning, I had tacos and chicken noodle soup," Larson said Thursday at TMS. "Later that night when I went to the hospital, I had pizza because that's all they had there. [Ganassi] says I need to lay off the pizza and tacos diet. ... My nutritionist Chip Ganassi is on me."

Larson already has returned to the seat of the race car. He spent all day Wednesday testing a Sprint Cup car at Richmond International Raceway and then part of Thursday in a Legends car as part of a mentoring program for sponsor Axe.

"I feel fine," Larson said. "I'm good. I'm staying hydrated. All is good. It was nice to get a day in before I got out here -- they ran all those tests -- just to make sure everything is good in the race car.

"It went fine. It went smooth. No problems at all."

Larson dropped six spots to 23rd in the Cup standings after missing Martinsville, where Regan Smith filled in for him and finished 16th.

"It's never good to miss a race," Larson said. "It will be nice to get back in."