I would be willing to be that as you walk and work out more, your energy levels will improve. I am a recovering coke addict and I know exactly what your going through in terms of the energy. Be careful when reading labels of food that say "fat-free." There is often alot of sugar and calories to watch out for.
Good luck.
By the way, if you ask your doctor about ECA, he will tell you not too on principle and give you advice like "eat a low-fat diet." That's fine, but you still have to watch the carbs and calories. It seems like you want to make a lifestyle change and get on a program you can sustain. The Atkins diet works great, but I would be careful in restricting carbs too much at this point, particularly with your current low energy level. Don't try to do too much too soon. You have the rest of your life to be fit. For every 1 person that keeps weight of in the Atkins diet, there are probably like 20 others that can't maintain it so get some exercise and eat a sensible diet and you'll start losing the weight and feeling better. There are many people on this board that are very advanced, and some of the diet techniques, while valid, are really not for beginners.