Popcorn is not suitable for Phase One of the South Beach diet, because dieters are encouraged to cut out all carbohydrates in this phase. Popcorn is allowed in Phase Two of the diet.
Even though the South Beach Diet is not a low-carb diet, it recommends reducing the amount of carbohydrates for the first two weeks, which are also referred to as Phase One. According to the Mayo Clinic, Phase Two is a long-term weight loss period and allows the reintroduction of carbohydrates into the diet. Air-popped and microwavable popcorn are suitable as snacks during this phase, which lasts until the weight loss goal is reached.