Always nice to have one's intuitions confirmed: that diagnosis is highly dependent on pre-conceived notions. I've always chafed at the marginalization of boys in eating disorder literature and discourse. I've always suspected that if society and doctors and especially parents knew what to look for that we'd be diagnosing AND TREATING many people who otherwise end up being seen as "picky" or "weird" or "very particular."
There's more in this analysis of the research than just the gender gap, but I remember when a few years ago a pretty large study indicated that the numbers of male ED patients was more like 1 in 5 rather than the usual 1 in 10 - that it just disappeared from sight. I suspect people just couldn't fit that into their thinking so they just keep repeating the old stuff. The problem of constantly recycled old information is a big problem.