Why's he telling me what to eat?

Okay my boyfriend knows I have an eating disorder which I'm overcoming and I'm actually eating a lot more than I did, but I'm getting there, and he saw a picture from today and he didn't say anything and about 10 mins after he was like you need to eat more veg, drink loads of water, eat fruit, as it will help you're tummy... Like why is he talking to me like that? I told him I have been so far, but he randomly came out with it yeah I admit I guess I look kinda skinny in the pic but he doesn't eat veg or have fruit lol but he wants me too? Also he is a doctor. How can I tell him I'm fine?
Why's he telling me what to eat?
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