Any time you change your diet for the better, you're going to feel better. You're eating less sugar, more vegetables, more protein, whole grains instead of white, and probably a lot more unsaturated fats and less saturated. You quit eating junk food and started eating foods with antioxidants and other compounds that heal. You're likely drinking more water and walking more. All of those things make people feel better. It doesn't really matter whether it's South Beach or DASH or what; just paying attention and caring about eating well is going to do the trick.