Mar 9, 2011 20:51 GMT  ·  By

After the latest ads for Armani underwear with Megan Fox premiered, many have said that she was looking so incredibly thin and frail that chances of an eating disorder were strong. Her trainer, Harley Pasternak, denies such rumors.

Hollywood Life got to speak with Megan’s trainer, who’s quick to deny all those ongoing rumors about the possibility of an eating disorder, saying the star is actually naturally tiny.

Not only is Megan thin by nature, she’s actually working hard to staying healthy, making sure she’s always in top shape.

Even more, Pasternak says, she has moments when she’s trying really hard to keep the weight on because she has such a quick metabolism and doesn’t put on weight regardless of what she eats.

“Do I worry about Megan getting too skinny? Yeah!” Pasternak says in light of the many comments that Fox is too thin.

“Believe it or not she has this really fast metabolism. So her training is all about body toning and sculpting. With her it’s really about she’s eating enough of the right things. People thought ‘Oh she must be anorexic’ but she’s far from that!” the trainer adds.

Pasternak also works with Robert Pattinson, Amanda Seyfried and Katy Perry, but Fox is the only one who actually has to put in a lot of effort to gain weight.

“She gets frustrated at times because she’s like ‘I need to put on weight.’ So she actually weight-trains to keep on that lean muscle tissue,” the trainer says.

This would explain why Megan is rocking a well-defined six-pack right now.

“The key to Megan’s abs is first of all genetics. The second is that we train her abs on all three planes. It’s not just about crunch, crunch, crunch. It’s about working her body up and down and side to side and rotation,” Pasternak says.

In the past, the gorgeous actress has hinted that she had some issues with eating healthy, but she refused to elaborate on them because she didn’t want to become a role model for anyone.

For the ad that started (again) all this talk of whether she’s too skinny or not, the Armani ad, see here. *Some discretion is recommended when watching this, since it’s a lingerie ad.