Back to the original subject... Adkins isn't a good choice if you have exercise on your mind. Your body needs carbs for exercise. Cut those out and when you exercise your body will try to use protein as an energy source, which does not produce optimal results for one, but doing this also releases byproducts which are hard on your kidneys. So, Adkins and exercise aren't exactly the best of buddies. If you're exercising, you really need to incorporate complex carbs. You can still totally do away with sugar and refined carbs such as white bread and have great results while exercising, so if your idea of Atkins is limited to this, then there's no problem. Going beyond that is where it gets questionable, if not downright bad, especially if you're strength training or otherwise doing high intensity activity that uses fast twitch muscles.

It's not good for the long haul.