You learned to use food as a way to deal with stress (or, some other emotion, or a lot of different emotions). You can't just say, "I'm going to stop doing this." You have to learn how to deal with these emotions in another way. This takes some experimenting -- what works for some people isn't going to work for someone else. But, I find there are really three things a person in this situation should do for the best possible "cure."
First, distraction is a good technique. Learn to delay the reaction as much as possible. When you get the urge to eat from something other than true physical hunger, make a rule that you have to drink a glass of water first, then wait 20 minutes. If you still feel like eating, see if you can delay again. You're not saying "NO" but if you delay enough, you may find the urge passes. Once you experience that a few times, you'll start learning that just because the voice says "eat" doesn't mean you have to, and you feel better anyway, without the food.
Second, it's important to find a REPLACEMENT for the food when delaying isn't working. Sure, you can find lower-calorie foods to use, and, as you've already done, make wiser, less destructive choices. Those are definitely steps in the right direction. But, it's also important to experiment with non-food stress relievers. As already mentioned, exercise is a good one. Daily exercise helps with general stress relief, but in-the-moment, going for a walk or even taking 10 minutes to do some stretching and deliberate breathing can help. Other tactics are journaling -- writing down why you're stressed and why you want to eat, talking to a friend, working on a hobby, listening to music, meditating, reading, working a crossword puzzle, etc. etc. Not only are many of these delay tactics in and of themselves, but the actions are proven stress relievers. Just think -- what makes you feel more relaxed and calm that doesn't involve food?
Finally, I think this is usually overlooked but in a way is the most important of all -- learning how to mitigate stress before it happens. If you are stressed because you have too much to do, or feel put upon, or angry at the way someone treats you, or WHATEVER -- think about what you can do to change that situation. If you're being walked all over, speak up. If you have too much to do, figure out how to prioritize and dump some of the load. When things still happen -- or if it's something truly out of your control -- then learn to manage your reaction and not be so stressed about it. The AA prayer isn't "God grant me the serenity to accept the things I cannot change, courage to change the things I can, and the wisdom to know the difference" for nothing.
Eating right and losing weight isn't JUST about discipline -- it's about learning what drives us to eat and developing real, practical strategies to deal with those issues. It's not just about NOT eating -- it's about doing what we should be doing INSTEAD of eating.