Atkins doesn't mention percentages, but quite a few other low carb plans do. All the percentages are different. A lot depends on if you are following a ketogenic diet (like Atkins). If so, your percentage of carbs will be very low. On other low"er" carb plans (ie. The Zone, Sugarbusters, Somersize, etc.) the percentages are more like 40%/30% fat/Protein, 30%carbs.

I did Atkins for the first 4 months. Lost great on it, but stalled out. Now I'm doing my own low-carb plan using approximately the above percentages. I also found that on Atkins I didn't watch percentages OR count calories and I still lost (until the stall). NOw I have to count calories and keep them 1200-1400. I'm not hungry though, so I guess that's what it's all about. I DO have to be careful though--with a higher carb allowance it's easier to overdo. I'm following a pretty conservative version of sugarbusters. They allow 2-3 servings of what they call "starchy carbs" (ie. 1/2 C. brown rice, 100% stone-ground whole wheat bread 1 slice, 1/2 C. oatmeal). I never go over 2 servings in a day, and I spread them out throughout the day.