Megan Fox filmed Teenage Mutant Ninja Turtles sequel while pregnant

Megan Fox lost weight shooting the Teenage Mutant Ninja Turtles sequel because she was constantly hungry on set.

The Transformers star hit headlines when she arrived at the CinemaCon event in Las Vegas to promote Teenage Mutant Ninja Turtles: Out of the Shadows with a noticeable baby bump on Monday (11Apr16).

Megan did not reveal the identity of her third child's father, but told People.com about the difficulties she faced filming the action movie while pregnant.

“I’m always in the process of having a baby and looking like I didn’t have a baby,” she said at the event. “I was training. There was no access to healthy food on the set so I ended up losing weight because I was hungry all the time.”

She told the website "the healthiest thing you’ll find" on set were rice cakes with almond butter and jelly, which became her go-to snack.

Megan, 29, discovered she was pregnant with her second child while filming the 2014 Turtles movie and she told talk show host Ellen DeGeneres that year (14) that it was a challenging experience.

"I got pregnant with Bodhi two weeks into filming Ninja Turtles, which is an action movie and requires a lot of running and jumping and stunts," she said. "Anyone that's been pregnant knows your first trimester can be pretty rough and you're nauseous all day long... I spent the whole shoot basically... on the verge of vomiting... and running and screaming."

Megan is already mum to Noah, three, and Bodhi, two, with estranged husband Brian Austin Green. Megan filed for divorce from the actor in August, 2015 after five years of marriage.