No, it was literally government policy. The free market didn't give us the McGovern committee or the following half-century of subsidies, regulations, and guidelines to promote low-fat diets.

Markets don't exist in a vacuum. In this case, it was substantially shaped by state-driven incentives. If nothing had changed, we wouldn't be having this conversation. It's a historical fact that something did change: https://en.wikipedia.org/wiki/Obesity_in_the_United_States#/....