Fat people make the best consumers by far. They're also far less likely to do anything anti-establishment as the establishment is the only real reason they survive in the world.

There is no societal benefit to having obese people. No government should ever actively promote obesity, it makes no logical sense for them to do so. It costs the taxpayer money and burdens the health system. A corrupted government owned by an oligarchy though...

Also, the sciences are being actively co-opted to push obesity. Example:

https://labblog.uofmhealth.org/body-work/fat-shaming-wont-solve-obesity-science-might

This is the exact same rhetoric as being used in the US for black on black violence, you remove the ability to fix the problem by forbidding people to say that there is one. If you mention the problem, and aren't attributing it one of the pre-approved causes, it is then highly offensive and you are a piece of shit for doing so. You are, in fact, a subhuman and will be constantly reminded as such.

To get back on topic - plenty of countries other than the US openly fat shame, such as slavic countries or Asian countries. They don't have an obesity problem.