The doctor on the emotional eating expert forum has great advice too. You should try there.
A lot of people have the same issue - it's great that you recognize it.
One approach is to deal with the things that cause you stress in the first place. Another is to try to think about why stress makes you overeat. One thing you could consider doing is creating a food diary where you write down what you are about to eat. This will give you a minute to confront the fact that you are eating a jelly donut in the middle of the afternoon for no apparent reason. Sometimes that moment of accountability will help you make a different choice.