Visual guide to the most popular low carbohydrate diets, including The South Beach Diet, the Zone Diet, Atkins Diet. Low-carb diets such the Zone and Atkins Diet are based on the idea that not all calories are alike. Low-carb plans, emphasize eating a balanced diet with a focus on healthy fats, protein, and dietary fiber. While many nutrition experts recommend fat reduction, low-fat diets are associated with the least calorie and energy expenditure. This means that low-carb diets offer metabolic advantages.