If your favourite comfort foods are not the healthiest options out there, this research will be of interest.  It found that the comfort factor is an illusion.  

Researchers at Pennsylvania State University say junky comfort food isn't truly comforting when you're dreaming about it beforehand or while you are eating it and to boot, it can bring you down afterward.  

In their experiments, they noted little in the way of mood changes before and during consumption of unhealthy comfort food and a significant dip in mood afterward.  That dip is linked to post-eating regret centered around body image and the knowledge that you should be making healthier choices.  

For the study, 131 women carried hand-held computers and logged their dietary choices and mood multiple times each day.