Atkins is about eating fewer carbohydrates in a controlled manner i.e. it is a low-carb diet. Phase 1 allows eating 20 gm of carb per day for 2 weeks. Phase 2 is about finding your carb tolerance, i.e. keep increasing your carb intake and still can lose weight to maintain your weight loss goal. Phase 3 is about slowing the weight loss acceleration achieved due to the previous two phases and building your carb tolerance. Phase 4 is your result phase where you have found your nutritional balance and carb tolerance to be on your goal weight.