"You'll be better able to maintain your weight loss if you don't have to permanently eliminate or restrict a single food group," explains Densie Webb, R.D. Low-carb diets are designed for short stints because your body simply cannot function without carbohydrates for very long. Diets that have this as their weight loss technique are appealing because they promise quick results, but studies show that after 12 months, they provide no greater weight loss benefit than a typical reduced-calorie, low-fat diet. Slow, steady weight loss is much easier to maintain for life, says Elisa Zied, R.D., a spokesperson for the American Dietetic Association.