Since when is it not attractive to be buff?

Now adays it seems girls are more attracted to these skinny/scrawny guys than the bigger and buff ones. I work out almost every day and I have had girls tell me I work out too much and that I am too buff. I dont get how some one can be "too buff" ? Last time I checked hitting the gym and building muscle was supposed to get you more girls but for some reason I am seeing these girls dating guys that weigh less than they do. Im sorry but that is just not hot. So for the females out there please explain why all of the sudden it is hot to be skinny but being buff and working out is a bad thing?