While some stars may be fretting over fitting into their frocks at the Oscars on Sunday night, Charlize Theron isn’t counting calories.

The sexy star, who’s dating Sean Penn, was spotted Thursday at a Hollywood In-N-Out Burger on her way to rehearse as an Oscar presenter at LA’s Dolby Theatre.

“She walked in wearing jeans and a pink top, then stood on line to order a burger during the lunch rush,” said a fast-food spy.

Theron then “got into a black Lexus SUV, burger bag in hand, and drove herself away!”