The main advantage of the low-carb diet is that it causes you to want to eat less. Even without counting calories most overweight people eat far fewer calories on low carb. Sugar and starch may increase your hunger, while avoiding them may decrease your appetite to an adequate level. If your body wants to have an appropriate number of calories you don’t need to bother counting them. Thus: Calories count, but you don’t need to count them.
In a way, moderate-intensity physical activity is that "magic pill" a lot of people are looking for, because the health benefits go beyond keeping your waistline trim: Not only can it reduce your risk of cancer, stroke, diabetes and heart attacks, but studies have shown that physical activity can significantly improve the moods of patients with major depressive disorders.