I find that, like it was with myself, it can stem from personal dissatisfaction and low self-esteem. Since food offers that instant gratification, the relief from feeling empty inside and filling yourself with the sensations of eating/consuming food, I find that the best strategy is to find NEW WAYS of filling that gap. Apart form cognitive behavioural therapy, which is basically being 'mindful' about how you are thinking and catching yourself out before you turn those thoughts into unhelpful behaviours, there's a number of approaches I have found helpful:
You can tune in to the podcast Beyond the Body to listen more about overcoming body image and eating disorder issues!
Presented by Thomas Grainger