As usual it comes down to the increasing individualism, that rejects any overarching societal guidance in favour of judgement-free self-expression ("body positivity"). This removes any collective bargaining or collective action (some of which I proposed in my parent comment) and exposes the individual to systemic risks (food industry making people fat, medical industry giving them a pill to feel better), unless the individual is equipped with enough of Bourdieu's social capital to navigate the pervasive health risks of the modern food supply. Allowing this minefield in place is also a convenient way to maintain class, leaving the unwashed masses hampered by health issues (like diabetes), reduced cognitive function and less attractiveness.