I agree, the topic of suicide comes up with those experiencing ideation easily but it is a different matter to discuss and encourage following through with it. If you value your friendship I would encourage her to find help. Maybe even offer to go with her if she would like the support.

Now, my appauling little knowledge of anorexia is that the condition often arises as a power and control issue. That, perhaps, the individual has such lack of control in their life that the one thing they can control is their body. In some of these cases outside control or power is exerted over them.

Thus, one way you may be able to help your friends is to find ways for her to control other situations in her life. Just a thought.