Hot actress Ali Larter is taking time out to become a role model for her teacher sister's young students.

The Legally Blonde star regularly shows up for one of her sister's classes - to help young girls who are struggling with image problems.

Larter admits how difficult it can be growing up - she became a model at 13 and faced a constant battle to keep her weight down.

She says, "I remember having my thighs taped back for a magazine spread and really sick things like that. I was a kid and the weight thing was a big for me.

"My sister is a sixth grade teacher and I talk to her class every now and then. I watch these little girls. If I go in and I'm wearing blue, they are wearing blue the next day.

"They are so impressionable. It's important that the girls know that you're lit well and you have make-up and they airbrush you nobody looks like that when they're walking down the street."