[dacryn]

or has the fast food industry and unhealthy eating habits in general, which lead to obesity, been the instigator of the mental health epidemic? Fix the food, fix the epidemic?

This is one of those cases where I think it's not one creates the other. But I assume they have a strong feedback mechanism. It's the combination that makes it a lot stronger. 2 + 2 = 5 in such cases

[_yb2s]

Yes, probably a feedback loop. There is lots of research showing modern food is engineered for high "food reward value" which overcomes our satiety mechanisms, and is essentially addictive (e.g. https://www.stephanguyenet.com/thehungrybrain/). Not to say that modern processed food isn't also quite unhealthy - with mental health implications, I suspect it is the food reward aspect itself that is mostly responsible for what you are talking about.

This I think has simply caused food to essentially replace alcohol as the default way to escape painful emotions- whereas the men traumatized in the big wars of the 20th century often became regular binge drinkers afterwards, I think food has largely replaced that.