There is limited research on the long-term safety of ketogenic diets, so it's not clear whether they are safe to follow for extended periods of time. Some concerns that have been raised about long-term ketogenic dieting include the potential for nutrient deficiencies, increased risk of kidney stones, and the impact on bone health. It's important to work with a healthcare provider or registered dietitian to monitor your health and nutrient status if you plan to follow a ketogenic diet long-term.