I'm currently seeing a trainer/nutritionist. According to him, diet is the biggest part of the change. I don't know about the Atkins diet, and I'm not sure how eating more vegetables will help other than reducing the urge to eat other things, but I have a bit of a gut as well. I've been told by the trainer/nutritionist that to get rid of it, eliminating carbs is the fastest way to go. He's got me on a high protein, no carb diet. If I'm having trouble sleeping he'll let me have some low-glycemic carbs like a handful of quinoa at dinner. Also, a palm-ful of berries to help ease cravings.
As for exercises, walking is fine but if that's a problem, maybe more stationary exercises would be better? For example, after doing planks I can barely sit up because my abs are so exhausted. My exercise routine is basically interval training - heavy weights, take a 30-60 second break, heavy weights, 30-60 second break, etc. It's low-movement cardio. Although, I'm kind of terrified that it will bulk me up, which I definitely do not want.