It's hard to get two paragraphs into anything written by a fat acceptance blogger without mention of how the diet industry has warped all of society's thinking about weight. They talk about how their raison d'être is to make us hate our bodies so much that we will fork over our cash to have ourselves "fixed" using their various programs. People who are comfortable with themselves aren't likely to buy as many goods and services as those who are uncomfortable, so the diet industry plays on insecurities that it manufactures according to many people who support body acceptance.
There is an assumption, and this is not only true of those who blame the diet industry for our body hatred, that "society", "government", or "business" make a decision and then indoctrinate us into their way of thinking. The feeling is that they decide how best to profit by manipulating us and then carry out a plan. As time goes by, they fine-tune that plan and play more expertly on our fears and pain to maximize their ability to cull our cash or gain power.
Here is the thing, and people don't like to accept this because a conspiracy is much more appealing than the truth, business does not create the environment of body hatred. It plays on feelings and insecurities that are already there. You are not sold something because someone tells you you should want it. You are sold it because on some level you already want it. No one can convince you of something which is absolutely not within your mind to some extent already.
The way business and government work is like building a fire. They see a spark, a flicker, or a tiny flame, and they fan it until it is bigger. If you allow them, they will create a raging bonfire, but some part of you is the origin of the inferno. They cannot make something from nothing just as you can't build a fire from nothing but a pile of twigs. This applies to government as well. If people vote for a wild political platform offered up by some crazy politician, it isn't because they are told what to do, but because it reflects what they already believed.
The grim truth is that all aspects of society are a reflection of the people who live in it. We get the government we deserve. We have a media which reflects what we want to hear. We are sold products which we want to buy. People say they feel differently, but then their behaviors and choices betray the truth. Fat women say they love their plump bodies, yet talk about how they can get thin, hot boyfriends. Why even mention this unless this is seen as a more prized condition than having a fat boyfriend? It's essentially seen as saying, "see, despite my inferior status in society, I can get someone of what is perceived to be a superior status."
So, the diet industry didn't teach us to hate being fat anymore than they taught us to hate the smell of body odor. They expertly play on our lack of love for various conditions. Despite what fat activists would like everyone to believe, being fat has been a disliked condition for centuries. Ancient Egyptians were body conscious despite having no organized diet industry or media programming. While there has been some flexibility in what is seen as an "ideal" form, that flexibility does not often extend to obese bodies.
Aside from the Venus figurines, there is very little historical evidence that grossly overweight forms were seen as beautiful even in ancient times. The Venus figurines are often held up as an example of ancient love of the rounded form, but such interpretations are wishful thinking at best. Given the emphasis on a large belly and breasts, they are much more likely to have been fertility images, not a celebration of fatness.
The bottom line is that most people don't like being fat. They've never liked being fat and the diet industry sprung up as a result of that dislike. It heard us talk. It knew how we felt about this condition and it acted to sell us something it was pretty sure we'd buy. The diet industry didn't make us hate our bodies. They simply are supplying a demand created by pre-existing hate of our condition.