Warning - vague pondering about research result coming.
According to "what makes you click" paper (first google hit, I cannot link), which measured who people actually first-contact on online dating (and people first-contact most attractive people most, not much shyness was found), men like short women with bmi around 17 most, while women like tall men with bmi around 27 (it's a random sample, so very few of them have actually that much muscle, so women like somewhat fat men).
The main reason seems to be pattern of men wanting women as thin as possible, and women wanting men of similar bmi to theirs. After reading the entire paper a few times, I believe this result might be true, and not result of some research artifact. I asked the guy who wrote the paper if he could provide me with detailed breakdown by woman weight, but didn't get a response.
What do you think of this? I'm at supposedly unattractive bmi 22 and I definitely don't intend to get fat just because of that, maybe I'll get some extra muscle. Does it simply mean that thin women will want me, and fat won't? I can live with that

. Or will getting more muscle lose my chances with slim women?