A study in the UK shows that eating a diet high in fat and sugar can raise the risk of depression.
https://www.theguardian.com/society/2018/sep/26/eating-junk-food-raises-risk-of-depression-says-multi-country-study
Personally, I always end up with a few more than normal junk food type meals when I travel. It might explain why I’m usually a bit down when I get home.
Any one else?