70s skinny

My mother uses the term "70s skinny", describing how people were just a different kind of skinny at the time. And when I look at photos from the time, she has a point. Boys and girls were really skinny. A few years ago, I was really skinny and in good shape. I asked her whether I was 70s skinny, and both my parents replied that I would never be 70s skinny. They told me that I look good, but that I would never fit in the 70s.
So what really happened to us? Why are we so bulky? Is it the excess of calories, the processed food, or the sheer meat intake? Regardless, I feel like some sort of brutish freak for not looking like them. They were the perfect functional humans, and now, we are just a bunch of Gorillas. (Nothing aginst the Gorillas, they are more gentle than us, we shouldn't even be compared.)