Its a misconception that you need to diet (as we've been taught) to lose weight. There's a small percentage of people who diet and it works for them (5% to be precise), but for most of us, the problem sits in our minds, not in our mouths, and it is this that needs to be addressed.
It is our relationship to food that needs to change. How to change this? You change it by addressing the root cause of why you started overeating in the first place, and then you can either re-train your taste buds with a juice fast, or simply begin adding more good food to your daily diet.
You can check out the online weight loss program for people who suffer from food addiction on the Get Thin for Good website.
As to exercise...it's kind of important to exercise for so many reasons, one of them is to develop self-discipline (something you would also learn on the Get Thin for Good program), and the other is for health reasons.