So, I have a friend who is depressed and cuts himself, and is suicidal. But I'm most worried about him because he is anorexic (yes people, it's not just girls that do that). He's fairly normal/thin, but he sees himself as fat. When I pointed out that his ribs show, he said he likes them that way, and he still thinks he's overweight. I'm really worried about him because I don't want him to hurt himself any further, but I'm not sure what to do to make him understand that he doesn't have to harm himself.

The cutting thing, let him ride it out, unless he starts makking attempts at slitting his wrists. Then get him help.
FUCK OFF HATERS, i say this from experiance.

As for the anorexia...
Get him help. Now.
Cutting is something people can cure on their own.
Anorexia is not.

Sounds like a job for a professional (depression? cutting? suicidal? anorexic? are you kidding me?). Get him to a therapist.

Do his parents know about these problems? Talk to them and see if they can't set up an appointment for your friend.

Talk to you his parents immediately. If you really care about him, you won't mind if he hates you for it as long as he gets the help heneeds.

I don't know his parents~ :( I'm not really sure what to do or how to get him help~

Ask the school for his home number.

I think there must be something bad, which makes him becomes so anxious and even begins to hurt himself. Ask him what happens on him, how dose he feel and why he cut himself.
And I agree the comments above, you should tell his school and his family what happens and take him to the therapist because Anorexia is hard to cure without some professional skills and knowledge and when it get worse, it will become dangerous