I find that you have to take a deep breath and just say it. If you try to plan it too much it'll just freak you out even more. Wait for a time when it's just the two of you and just say it when no one's talking.
EXACTLY. I struggled with anorexia and that's exactly how I told my mom. If you try to make it super elaborate then you'll just make yourself more nervous. Be straightforward and to the point. This is an excellent thing to say. Don't over think it, your mom loves you and she'll do what's best for you!