Update

Selena Gomez: I Was 'Malnourished' and 'Exhausted'

By Patrick Gomez and Melody Chiu

UPDATED 06/14/2011 at 07:15 AM EDT • Originally published 06/13/2011 at 07:00 PM EDT

Nothing can heal a teen pop star faster than a shopping mall filled with screaming fans.

Selena Gomez appears to be on the mend, taking the stage Monday for a Santa Monica Place show that had to be rescheduled from Friday due to her hospitalization.

"I want to thank you so much for coming," Gomez, 18, told more than 500 young fans at the outdoor mall. "If you guys came on Friday, I'm so sorry that I couldn't be here. ... I love you guys very much."

RELATED: Selena Gomez 'Feeling Much Better' After Hospitalization

Asked by reporters for the cause of her hospitalization, she said, "I was just very malnourished, so I was low on iron and exhausted."

Showing no signs of those health problems, an energetic Gomez performed "Who Says" and "A Year Without Rain" and bantered with the crowd, telling the fans, "I do feel better!"

• Additional reporting by GABRIELLE OLYA