Ketogenic diet is a high fat diet with moderate protein content and a very low carbohydrate allowance. It aims a treducing the average calorie intake by minimising carbohydrates and replacing them with healthy fats and moderate amounts of high-quality protein. This causes the body’s internal biochemical pathways to switch to using its stored fat for fuel instead of utilising glucose.
Put simply, as blood-glucose level in the body drops, the liver starts to produce ketones — a process that shifts the body cells towards fat utilisation as an alternative source of fuel.
A ketone-producing diet is terrific for weight reduction, body renewal and diabetes management. In fact, being in ketosis can offer hope against cancer, both for prevention and treatment. The antioxidant and anti-inflammatory effect of nutritional ketosis can be used to address many metabolic diseases.
The ketogenic diet is not a new treatment in addressing chronic diseases. Throughout history, it has been recognised that if a person with epilepsy stops eating (fasts), their seizures generally stop. Physicians of ancient Greece treated diseases, including epilepsy and obesity, by altering their patients’ diet. However, the classic therapeutic ketogenic diet was developed for treatment of paediatric epilepsy in the 1920s and was widely used into the 1930s, but its popularity declined with the introduction of effective anticonvulsant drugs.
Fuel metabolism and the ketogenic diet
There are four sources of calories for the body: carbohydrates, protein, fats, and alcohol. The body tends to utilise a given source of fuel for energy in relation to its availability and concentration in the bloodstream.
Carbohydrates are the most preferred source of calories because they can be broken down quickly to glucose, the main metabolic fuel of the body. However, the body can increase or decrease its use of glucose in direct proportion to the amount of dietary carbohydrate consumed. Fat utilisation is dependent on carbohydrate and alcohol consumption.
Ketogenic diet aims at reducing the average calorie intake by minimising carbohydrates and replacing them with large amount of healthy fats and moderate amounts of protein. This mimics starvation or fasting state as the body enters into a condition known as ketosis. Ketosis means that the body is in a state where it doesn’t have enough glucose available to use as energy, forcing it to metabolise free fatty acids as an alternative fuel.
Some tissues in the body(the brain, for example)cannot utilise fats for their energy needs. However, when the body is running primarily on fats, large amounts of acetyl-CoA are produced which exceed the capacity of the Krebs cycle, leading to the production of Ketone bodies (acetoacetate, â-hydroxybutyrate and acetone) which are by-products of the incomplete breakdown of free fatty acids within liver mitochondria and are readily utilised by the brain and heart muscles.
It is worth mentioning that some people confuse ketoacidosis, an extremely abnormal form of ketosis, with the normal benign dietary ketosis associated with ketogenic diets. Benign dietary ketosis is a controlled, insulin-regulated process, which results in a mild release of fatty acids and ketone body production in response to low carbohydrate intake, and higher fat consumption. On the other hand, Ketoacidosis is a condition in which abnormal quantities of ketones are produced in an unregulated biochemical situation.
In order to reach a state of ketoacidosis, the body has to be in a state of not producing enough insulin to regulate the flow of fatty acids and the creation of ketone bodies.
Ketogenic diet in metabolic disease management:
Source: A Paoli, A Rubini, J S Volek and K A Grimaldi. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition (2013) 67, 789–796
Ketones and cancer management
Normal cells have the metabolic flexibility to survive, in the absence of glucose, on other sources of metabolic fuel. Cancer cells lack this ability because of their broken metabolism.They are thus vulnerable to any diet which sharply lowers blood sugar. This is the main idea behind the use of a ketogenic diet to treat cancer – to deprive the cancer cells of the glucose they need to survive, and provide alternative fuel to support the mitochondrial respiratory processes in healthy tissues.
Dr Otto Warburg, one of the 20th century’s leading biochemists, discovered this about cancer and the hypothesis that cancer cells are only able to use glucose (blood sugar) for fuel is today called the Warburg Hypothesis.
Roles in neurological diseases
The keto diet is also being increasingly considered for the treatment of many neurological diseases and injuries, a list that includes Parkinson’s, Alzheimer’s, stroke, and even traumatic brain injuries.
Ketogenicdiets can also improve memory function in older adults with increased risk for Alzheimer’s disease. Neuroscientists attribute the keto diet’s brain-protective qualities to the following factors:
1. Ketone bodies serve as an alternative source of energy during metabolic stress
2. Ketosis diminishes the toxicity produced by glutamate acid, a problem when a brain injury happens
3. Ketosis enhances GABA levels (ã-Aminobutyric acid) — an important inhibitory neurotransmitter
4. The ketogenic diet has antioxidant and anti-inflammatory qualities
5. The diet protects against various forms of cell death
6. Restricting carbs protects against oxidative- and glutamate-stress, among other things
Considerations in diabetes
Ketogenic diet works effectually for people with type 2 diabetes because it is low in carbohydrate. It is effective in improving glycaemic control in diabetic patients. Some studies also show that ketosis helps reverse hepatic insulin resistance.
As with every other diet used to manage metabolic diseases, ketogenic diet also has its limitations. Therefore, it is important that any person considering the diet should consult a dietician or doctor who can advise him or her on the best way to approach it. Some of the side effects of this diet include constipation, hypoglycaemia, hypercholesterolemia, and hyperacidosis
Other negative symptoms occur during the first week of initiating the diet. They include: fatigue, weakness, light-headedness, headaches, and mild irritability. However each of these can be eased easily. Cheeringly, most the symptoms wane off after the first week of the diet.
Regulation of ketogenesis
(Sung to the tune of “Clementine”)
In starvation, diabetes, sugar levels under strain
You need fuel to keep going saving glucose for your brain
Ketone bodies, Ketone bodies, both acetoacetate
And its partner on reduction, 3-hydroxybutyrate.
Glucagon’s up, with low glucose, insulin is down in phase
Fatty acids mobilised by hormone-sensitive lipase
Ketone bodies, Ketone bodies, all start thus from white fat cell
Where through lack of glycerol-P, TG making’s down as well
…Don’t despise them, they’re good fuels for your muscles, brain and heart
When you’re bodies overloaded though, that’s when your troubles start
Ketone bodies, ketone bodies, make acetone, lose CO2
You can breath those out, but watch out – acidosis does for you!
Source: “The Biochemists’ Songbook, 2nd ed.” Harold Baum. London: Taylor and Francis Publishers,1995.
• Schmidt et al. Effects of a ketogenic diet on the quality of life in 16 patients with advanced cancer. Nutrition & Metabolism(2011)
• Lyle McDonald. The Ketogenic Diet: A complete guide for the Dieter and Practitioner (1998)
• Gasioret al :Neuroprotective and disease-modifying effects of the ketogenic diet. Behav Pharmacol. (September 2006)
• Paoli et al.Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition (2013) 67, 789–796