Which edition are you following? If it's the 2002 edition, there is a specific order to add back foods, and fruit, berries first, doesn't come up for a couple more weeks, and other fruits don't come up until several weeks after that. If it's the 1992 edition, you can add back whatever you miss most first. Both require the serving to be 5g carbs. And both warn that fruit is notorious for causing cravings and/or stopping progress.