There's playeatsleep for paleo/primal eating (I lean that way -- not interested in turning it into a cult or being rigid about it, but my body definitely seems to be happier given lots of fish, meat, veg, fruit and nuts, with some dairy and occasional grains on the side).

And cookability (cooking for people with limited spoon owing to disability or illness) seems to have a lot of recipes posted with attention to whether they're gluten-free, appropriate for specific dietary needs, and so forth.

Neither's exactly what you're looking for, but you might be able to open up some discussions there; it'd be good to see alternative eating comms like that discussing ways to be ED-safe.