The ketogenic diet (KD) typically provides a marginally healthy diet and in recent years has been used for more protracted courses of therapy. This results in concern about the impact of the diet on the general health of the child. Studies have demonstrated poor growth, dyslipidemia, kidney stones, and numerous other problems seen less frequently. Major areas of concern are reviewed as well as some emerging evidence of more beneficial long-term health consequences beyond the expected control of seizures.