The Ketogenic Diet (KD) is a medically managed and carefully calculated high-fat, low carbohydrate diet, designed to mimic a fasting state over a long period of time. It is available as a treatment option for children with difficult-to-control epilepsy and some neuro-metabolic disorders.
When on the Ketogenic Diet, a simulated ‘fasting state’ is achieved by forcing the body to burn fats to produce ketones rather than utilise carbohydrates. When there is very little dietary carbohydrate, the liver converts fat into fatty acids and ketone bodies. The ketone bodies then pass into the brain, replacing glucose as the primary energy source. This elevated level of ketone bodies in the blood is referred to as ketosis.
Although the exact mechanism of action remains unclear, when ketone bodies become the main energy source for the brain, it is thought to mimic the biochemical response to starvation1, a practice used historically to control seizures.
The Ketogenic Diet requires close medical and dietetic supervision and is trialled for a minimum of three months, and if effective, is generally continued for two years.
Process for achieving ketosis
- Carbohydrate consumption is limited to deplete carbohydrate stores
- Fats are subsequently metabolised instead of carbohydrates
- Mitochondrial beta oxidation transforms fatty acids into ketone bodies
- Ketone bodies (acetone, acetoacetate, and beta-hydroxybutyrate) accumulate in the blood, urine, and CSF
- This process affects seizure onset and propagation, and in many cases, leads to reduction or cessation of seizures
Types of Ketogenic Diet
The choice of the type of Ketogenic Diet prescribed for each individual patient depends on multiple factors including the underlying condition, the age of the patient, their capacity for oral intake and their food preferences.
- The Classical Ketogenic Diet uses fixed ratios of fat to carbohydrate/protein. A 4:1 ratio, for example, uses four grams of long-chain fat to each gram of carbohydrate and protein combined.
- The Medium Chain Triglyceride Diet uses medium-chain triglycerides such as MCT oil, Liquigen, or Coconut Oil.
- The Modified Atkins Diet has somewhat greater flexibility than the Classical Ketogenic Diet and allows greater amounts of protein. 2
- The Low Glycaemic Index Diet attempts to achieve stable blood glucose levels.3
All of these diets require close monitoring and need to be carried out under medical and dietary supervision.
Information last reviewed: 5/02/2021.
- 1. Neal et al. (2008). The ketogenic diet for the treatment of epilepsy: a randomised control trial. Lancet Neurol. 7:500-506.
- 2. Kossof et al. (2013). A decade of the modified Atkins diet (2003-2013): Results, inisghts, and future directions. Epilepsy & Behaviour, 29: 437-442.
- 3. Kossof et al. (2013). A decade of the modified Atkins diet (2003-2013): Results, inisghts, and future directions. Epilepsy & Behaviour, 29: 437-442.