Khloe Kardashian recently sparked rumors that she had facial surgery after appearing looking rather different during her book signing on Monday at Los Angeles's Barnes & Noble.

The 31-year-old seemed to have trouble smiling because her skin appeared so taught as if it has recently undergone plastic surgery.

Khloe stepped out for the book signing of her autobiography "Strong Looks Better Naked" looking totally unrecognizable. Aside from her new hairstyle and her weight loss highlighted under her revealing jumpsuit, the 31-year-old looked different too.

Wetpaint.com shared a couple of photos from Khloe's book signing event which showed her seemingly having a hard time putting on a big smile to her face. One picture shows the "Keeping Up With The Kardashians" star holding on to her book as she posed for the camera. However, it wasn't her naked photo on the cover of her book that intrigued fans. Instead, it was how she seemed to make a lot of effort smiling.

According to Life & Style magazine, it's clear that Khloe had some contouring make-up done on her nose and cheeks. But it was reportedly her facial skin that got people talking. Her skin reportedly looked so tight, which made if difficult for her to smile. In another photo shared by the publication, Khloe also looked like she had lip fillers done, similar to what Kylie Jenner did to her lips.

Back in September, Khloe also stirred plastic surgery speculations after people saw how her smile looking so stiff in a photo. Dr. Mark Youssef of Younique Cosmetic Surgery told HollywoodLife that the 31-year-old may have had Botox instead because her face had looked unusually swollen.

"This is most likely the result of too much Botox in the forehead. As a result, Khloe's eyelids look heavier, the arch of her eyebrows appear more prominent, and her forehead more elongated," he said, referring to her face in the photo shared by Hollywood Life.

"Typically the results of Botox make the face look the most stiff and swollen seven days after the procedure. Most likely, Khloe's face will go back to normal after the swelling goes down," Younique further explained to HollywoodLife, adding that Khloe also looked like she had fillers applied to her cheeks.

However, despite the plastic surgery rumors, Khloe had already made it clear in a previous interview with Redbook magazine for its December/January issue that she is against the process.