Thin's Always Been In?

Why is it that this society in the West puts so much on the opinion that if you're thin, you're automatically beautiful? Isn't that a relative term? Beautiful? People think skinny is normal, what would happen if curvy was the norm? Would everyone look down upon them? There is no double standard in this society when it comes to how you look. The influence always makes women have flat stomachs and be size zeroes, and men have chiseled muscles. This is definitely relative, because in India, not all celebrities are stick skinny. In fact, most aren't. They still look beautiful, and they're healthy. When did someone decide the ideal image? I don't know how else to write this, and I have so many different thoughts in my head, but I don't know how to put them into words on the computer, But do you get my point? It's all relative, and everyone makes it seem it's all it cracks up to be. Is it really so?