A friend lost 40 lbs. on Atkins. His wife lost 80.
They were very strict about it: no carbs whatsoever. That can get a little grim, though. I know another woman who lost 50 lbs. in a year, using a modified Atkins: she ate eggs and meat for breakfast, a salad for lunch, and then a "regular" meal at dinner, meaning she would let herself have potatoes or carbs like that, but she avoided white flour stuff.
She looked great (as do my friend and his wife): not that drawn, haggard look some folks have after losing weight.
I've recommended a very modified Atkins for folks with moderate weight loss needs, and it works well for many people: basically avoid white flour (white breads, pancakes, etc.) and white sugar. It has the advantage that most people can stick to it, too.
Jim Huffman, RN