I was on Atkins for a few months a few years ago. Yes, I lost weight on it. And I lost it a whole lot easier than I have on any other diet. The problems I had were that I had no energy (even walking up a half-flight of stairs tired me out), I couldn't think clearly (it was as if my thoughts were being filtered through a haze), and I had a hard time concentrating. I would think that exercise and Atkins wouldn't go well together.