The ketogenic diet (KD) is a critical, evidence-based intervention within medical nutrition therapy for managing neurological disorders. In this article, we reviewed the published research on the efficacy of the ketogenic diet and its variations in treating epilepsy, particularly for patients unresponsive to anti-epileptic drugs. The literature review was performed on PubMed between 2022 and 2025. The review of clinical studies across various age groups reveals that, while the KD is effective for both focal and generalized seizures, infants often achieve higher rates of seizure freedom compared to adults, potentially due to better dietary compliance. Despite its success, the restrictive nature of the diet presents significant challenges for individuals suffering from epilepsy. The key challenges that reduce compliance over time include side effects, such as gastrointestinal issues, potential for malnutrition, and a high risk of micronutrient deficiencies. The role of the registered dietitian is paramount in this interdisciplinary approach, ensuring personalized education by monitoring growth and adjusting nutritional plans to optimize health outcomes for children unresponsive to anti-epileptic drugs. Ultimately, integrating MNT with traditional pharmacological or surgical treatments offers the most promising path for significant seizure reduction and improved quality of life for epileptic patients.