Phase One Carb Consumption. Phase one of the South Beach Diet has the most restrictive carbohydrate intake of all the phases. During phase one, you will only consume about 10 percent of your daily calories in the form of carbohydrates, or about 50 g of carbohydrates per day for someone consuming 2,000 calories a day.uring phase one, you will only consume about 10 percent of your daily calories in the form of carbohydrates, or about 50 g of carbohydrates per day for someone consuming 2,000 calories a day.