When you know someone has an eating disorder it can be quite natural to try to label the problem. By giving it a name it can help us to make sense of it, and to mentally partition it as a separate issue. This is not particularly useful for the person involved, and it can be quite dehumanising. We should never label them, or argue with them that there is a problem. If you find yourself becoming accusatory in tone, try to reframe what you say to be more compassionate and understanding. Let them know, that problem or no problem, you are still worried for them and are there to help them find a solution.
No one-size-fits-all solution
When it comes to helping people with an eating disorder, its as simple as this - there is no one-size-fits all solution. An eating disorder has no single cause, and will be multifactorial in nature. They are complex issues. As a friend or family member of someone with an eating disorder, first do your best to learn as much as you can about eating disorders. If necessary, speak with a qualified therapist to learn more. Those with eating disorders can have a deep ambivalence and resistance to change which might seem at odds with other things they say. Make sure you've done your due diligence before you try to engage with them in depth.