Although the demographic is different than the usual, the opinions here are standard issue: wanting to be thin, identity, culture, desire for control, emotional solace. A set of behaviors, choices. There's a range of views here but not one describes eating disorders as a mental illness or biological in nature -- or with a significant genetic predisposition --or treatable, which I would argue are the most important facts.
Just the topic tells us so much. If the question was "do Black folk have diabetes?" there'd be a different frame here because we'd be talking about a disease that everyone recognizes for what it is. Nobody would be riffing on autoimmune theories and endocrinology - they'd talk about their sister who had it and their uncle who lost his toe from it. If the topic was cancer no one would even be asking the question: it wouldn't be seen as cultural.
We need clear terms and a clear view of what an eating disorder is so people will stop thinking of eating disorders as something everyone is an expert on, and start thinking of them as something people -- including black people -- not only have but recover from.
Oh, and before anyone says it, I will. Black folk aren't biologically or genetically different than white folk. Look it up. Black and white Americans are more likely to be related to their opposite race next-door neighbors than they are same race folks on the opposite coast. Race is a social construct, not a biological family. If that sounds odd to you think of hair or eye color. Think about it: are green-eyed people from different families more likely to be related to one another?