The ketogenic diet is a validated and standard non-pharmacological treatment for drug-resistant epilepsies and epileptic encephalopathies, with over a century of tradition.
While it is most widely used in pediatric epilepsy, it is also applied—although less commonly—in adolescent and adult patients. In these groups, more flexible adaptations of the classic ketogenic diet are often used, generally referred to under the umbrella term ketotherapy.
Ketotherapy is a modern and effective treatment, though still reserved for a relatively narrow and carefully selected group of patients. For this reason, its indication and management fall under the expertise of specialized epilepsy centers.
All forms of ketogenic diets are based on a strict reduction of carbohydrates and a high proportion of fats, leading to the production of ketone bodies in the body (ketogenesis). This metabolic state is considered the essential mechanism behind the anti-seizure effect.
Effectiveness has been confirmed for both generalized and focal seizures. In recent years, ketotherapy has shown particularly promising results for conditions such as myoclonic-atonic epilepsy, epileptic spasms, GLUT1 deficiency, Angelman syndrome, and super-refractory status epilepticus.
Ketotherapy has proven effective for both generalized and focal seizures and across all age groups. After excluding absolute and evaluating relative contraindications, it can potentially be considered for any patient with drug-resistant epilepsy. For some epilepsy syndromes, especially in children, where the response to ketotherapy is excellent, even prior confirmation of drug resistance is no longer required. Therefore, ketotherapy is not just a last-resort treatment—on the contrary, earlier consideration of this therapy is becoming more common.
Overall, the proportion of responders to the Modified Atkins Diet (MAD) and the classic Ketogenic Diet (cKD) is comparable. However, the likelihood of achieving complete seizure freedom is significantly lower with MAD. MAD is thus considered an effective but more palliative therapy, while in pediatric patients with the potential for substantial benefit, the classic KD is preferred.
In adult patients, the main challenge is poor long-term adherence to the diet (even to MAD). Additionally, unlike in children, the therapeutic effect in adults may not persist after the diet is discontinued.
The classical ketogenic diet (cKD) is the most established and commonly used form of ketogenic therapy in children. Its use in adults is more limited. It represents the strictest dietary protocol, requiring the highest level of compliance, but also offering the greatest ketogenic potential. Meals are calculated individually, and food preparation demands extreme precision in weighing all ingredients.
Most of the fat in this diet comes from cream, butter, oils, and other naturally fatty foods.
The initiation of cKD can be done in two ways — through an initial 12–48 hour fasting protocol or gradually via a non-fasting approach.
Up to 75% of patients experience benefits within the first 14 days of treatment, though real evaluation of effectiveness is usually conducted after 3–6 months. If clear benefits are observed, the diet is continued for two years, after which it is gradually discontinued or transitioned into a milder regimen. About two-thirds of children who achieve full seizure remission remain seizure-free even after returning to a regular diet. However, some patients rely on cKD long-term and continue it for several years.
The Modified Atkins Diet (MAD) is a more flexible form of ketogenic therapy. It has been used in epilepsy treatment since 2003. The meal plans are more palatable, and overall management is simpler — both patient education and therapy initiation are typically handled on an outpatient basis. MAD is used in pediatric, adolescent, and adult epilepsy cases where stricter regimens are not realistic.
Unlike the classical ketogenic diet, which heavily restricts all macronutrients, MAD offers greater flexibility regarding fluid, calorie, and protein intake. Patients primarily need to monitor only their daily carbohydrate intake.
The Low Glycemic Index Treatment (LGIT) is in many ways similar to MAD, differing mainly in the selection of carbohydrate sources. The net carbohydrate intake ranges from 40 to 60 g/day. LGIT focuses on foods with a low glycemic index, such as whole-grain bread, fruits, and vegetables, to avoid sharp spikes in blood sugar levels.
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