Anyone have ideas why back in the 60's - 70's people were thin, and now not so thin?

I like listening to 60's and 70's music, and im seeing lots of skinny chicks and guys at this concert. I havent really found anyone overweight in the audience "which is thousands of people" this saddens me.. I know its the way we eat now a days, theirs millions of people eating mcdoanlds every hour of the day. I just wish people would come to realize what its doing to them, but I guess people dont care anymore or some dont think they can change when its really not that hard. I dunno it just frustrates me and I want to hear other peoples opinions and see what you guys think about this. I wish their was something that can be done, But truely its up to each individual and I can not see that being of much affect... man.. I think ill stop now before i go on forever.. this pisses me off... this food is almost like a drug,being like crave it, its scary, and its killing people slowly, ahhh!!