Her publicist, Michael Pagnotta, denied Tuesday a report on NBC's "Today" show that the 18-year-old actress had suffered a setback and returned to Los Angeles.
"Somehow there's a suggestion that she has relapsed into an eating disorder (search)," he said. "That's just silly. She's in ongoing treatment for an eating disorder with an experienced team of professionals who are available to her on both coasts. She is working very hard at being well."
Pagnotta, in a statement, said Olsen is in Los Angeles for a few days on personal business "and will be returning to New York and to school shortly."
The New York Daily News also said in Tuesday's editions that Mary-Kate "has been playing hooky in Los Angeles."
Janice Min, editor in chief of US Weekly magazine, said on the "Today" show that the brunette half of the Olsen twins was under too much stress.
"She just got out of recovery when she came to New York," Min said. "For anyone who has been to college, the freshman year is stressful, and when you are Mary-Kate Olsen and having the whole world watch your behavior and what you eat was too much."
A story on Mary-Kate was to be published in the upcoming issue of US Weekly, the "Today" show reported.
Mary-Kate and her blond sister, Ashley, both attend NYU. They started out playing Michelle Tanner as babies on ABC's "Full House" and have created a multimedia empire with a clothing line, feature films, direct-to-video movies and other merchandise.