I'm kinda skinny but there are other things by far that make me unattractive.
Maybe your perspective is like this because you are on a site that perceives bulkier is sexier.
At the end of the day I think most people prefer someone healthy. Above that, wanting particular a person in a specific weight or size range is just fetish maybe?
Not sure but for some people it's more about the statement of your lifestyle.
For others it's really down to the appearance.
I don't know if there is a perception of skinny being effeminate, and that's a whole different issue altogether.
As cliche as it sounds you really just have to work with what you've got.
Someone told me once that you just have to accept that there are people out there who 'have' it better than you. For some there might not be as many, and for others there might be a lot.
Everyone is some kind of statistic, be okay to accept it, don't compare and just focus on the people who do care about you.
Some people are singers and some are dancers. Some are very smart and some are good with their hands. Some are very pragmatic and some are very intuitive. Some are aesthetically pleasing, and there are others that aren't as much. Some are a whole mix of these things and some are just a few.
At the end of the day, you're better off just doing you. Try to have a big heart and hope that one day what you have to offer is enough for someone.
My ugly and unattractive 2 cents