Junking Yourself?

A multinational study has suggested a link between eating junk food ands depression (https://www.theguardian.com/society/2018/sep/26/eating-junk-food-raises-risk-of-depression-says-multi-country-study). Although this could simply be a consequence of not taking in sufficient quantities of the necessary nutrients (and, perhaps, too much of the wrong foods), there are other possibilities. At the most basic, some people who eat junk food are just basically poor and a strong link between poverty and depression has been known for some time. It could also be the case that some regular consumers of junk food do so in a way that curtails their social interactions and that could have a detrimental effect on mental health. People who eat junk foods may also develop obesity, a condition that damages physical health, having a positive body image and a willingness to do exercise (all factors that might predispose individuals to depression). I suspect that different combinations of factors account for the link in different cases.