my parents know i have anorexia. how do i start hiding it again without them getting suspisious?

You don't. Or at least, you shouldn't. I think you know this, because why else would you ask such a question on a website that's designed to help people be healthier?

If you are not already or still seeing a therapist and nutritionist, I strongly recommend that you start. Anorexia is very serious and can result in many health complications. Please talk to your parents. They obviously care, if they're paying attention to make sure you aren't relapsing. 

Good luck. It is okay to need and ask for help... but no one here will give you the answer you might hope for to this question because it would put your life in danger.