You started seeing him knowing he had no experience with eating issues, so, that was your choice. He wasn't conning or taking advantage of you- you picked him over someone who specialized in this issue.

You chose to focus with him on three things that you list above: self esteem, relationships, depression.

How are you doing in those areas? Is the therapy helping?

I don't think this is necessarily anything to do with ethics unless there are more issues than you've mentioned above.

If he's not helping you, then you can certainly move on to another therapist who is better suited to the work you need to do, and I encourage you to do that since your disordered eating is becoming concerning! If you love the current therapist because you're making progress in other areas, well, you might consider seeing two or consulting with someone to help you transition away, something to make it easier for you emotionally.