Food and mood - is there any relationship?

I am pretty sure there are days that you are quite mad at something and decided to gorge maybe a whole pizza or a full bag of chips. Stress eating plays a big role in the current obesity epidemic in the U.S. There is contentious debate among scientists on how food habits impact our mood or emotions. Is there any correlation between food and mental disorder? Data from research is still short of making any conclusion, but there is growing evidence that what we eat can affect our state of mind. Depression rate rising among general population across various demographics. Depression is the leading cause of disability in the U.S. for ages 15 to 44.3. Major depressive disorder affects around 16.1 million American adults or about 6.7%of the U.S. population age 18 and older in a given year.

A number of epidemiologic and observational studies found a link between our eating habits and depression. A study published in Brain, Behavior, and Immunity in 2014, found an association between depression and a diet rich in high sugary food like doughnuts, chips, beverages, ice-cream etc. Inflammatory diet (a diet rich in pro-inflammatory food like processed or fried food),  can increase the risk of developing depression; according to another study published in the same journal in 2015. A meta-analysis reported at European Journal of Nutrition in 2018 suggested high meat consumption may cause depression.  

Science is not there yet to pinpoint any direct causal relationship between a specific diet and depression. Depression is a multifactorial disease and more research needed to answer this question. Considering the impact of mental illnesses on overall health and wellbeing, it is imperative that we find the answer sooner.

If you want to read more about the studies, here are the links:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745880/

https://www.sciencedirect.com/science/article/pii/S0889159113004698