Why don't we consider fat people attractive?

[That Guy]

Or rather; when did society decide that fat chicks weren't attractive?

 I find it funny that society has decided for us what was deemed attractive and unattractive and most of us pretty much agree. 

I wonder how much of someone's attractiveness is based on 

1) our personal preferences and

2)  how that someone measures up to society's standards of beauty

I don't think its 50% - 50%. In fact, I would probably say its more like 10 % of our personal preferences and 90 % society's standards.

 

Or is it even something completely different alltogether? Is it sociological? Biological? Evolution? I don't know.