When you want to investigate something using the scientific method, first you create a model that you hope describes a natural phenomenon-- this is called a hypothesis. Then you go about testing that model against reality, under controlled conditions, to see if it has any predictive power. There is rarely a single experiment, or single study, that can demonstrate that a hypothesis is correct. Most important hypotheses require many mutually buttressing lines of evidence from multiple research groups before they're widely accepted. Although it's not necessary, understanding the mechanism by which an effect occurs, and having that mechanism be consistent with the hypothesis, adds substantially to the case.
With that in mind, this post will go into greater detail on the evidence supporting food reward and palatability as major factors in the regulation of food intake and body fatness. There is a large amount of supportive evidence at this point, which is rapidly expanding due to the efforts of many brilliant researchers, however for the sake of clarity and brevity, so far I've only given a "tip of the iceberg" view of it. But there are two types of people who want more detail: (1) the skeptics, and (2) scientifically inclined people who want mechanism. This post is for them. It will get technical at times, as there is no other way to convey the material effectively.
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