A ketogenic (or ‘keto’) diet is an extremely-low carbohydrate diet that is sometimes used as a medical treatment for certain groups of people. The ketogenic diet is sometimes confused with a general ‘low-carb’ diet or promoted as a weight loss technique for healthy people. But it is not recommended for the general population.
What is a carbohydrate?
Carbohydrates, or ‘carbs’, are an important nutrient. They are an excellent source of energy for the body and brain and most foods that contain carbohydrates also provide vitamins, minerals and fibre for good bowel health.
What is the ketogenic diet?
On a ketogenic diet, people eat a very small amount of carbohydrates, a moderate amount of protein and a large proportion of fat per day. This means that the body uses fat as its main source of fuel and breaks it down into ‘ketone bodies’ (or ‘ketones’) in a process called ketosis.
People on a keto diet usually eat only 20–50g of carbs per day. As an example, 50g of carbohydrate is equivalent to 2 slices of bread and a banana.
Carbs make up about one tenth of daily kilojoule intake in a ketogenic diet (a kilojoule is a measure of how much energy we get from food). This means the person’s body stays in a constant state of ketosis.
Evidence shows that the diet may be suitable for some people with certain medical conditions but should not be used for the general population, or as a long-term diet.
Who is the ketogenic diet for?
Evidence suggests that a keto diet, under the supervision of a qualified doctor or dietitian, may be useful for children with epilepsy who continue to have seizures while on antiepileptic drugs. It may be useful in cases of brain cancer, although further studies need to be done on humans before this can be recommended.
For people who have type 2 diabetes, a ketogenic diet may improve blood sugar control in the short term. However, the long-term effects are not known, particularly on people’s cholesterol levels, which increased in some studies.
The ketogenic diet is often promoted for weight loss in healthy people. Although it has been shown to be fast and effective in the short term, it is not known whether staying on a ketogenic diet is safe and effective over a longer period of time. In the long term, the safer Mediterranean diet or a standard low-fat diet can have the same result.
What to expect on a ketogenic diet
A typical ketogenic diet significantly reduces a person’s intake of rice, pasta, fruit, grains, bread, beans and starchy vegetables such as peas and potatoes. For example, the Dietitians Association of Australia says that this could restrict you to the carbohydrate levels of only a small tub of yoghurt, a medium-sized potato and one apple per day.
Because it’s very limiting, a large number of people tend to drop out of the diet, contributing to unhealthy, ‘yo-yo’ dieting behaviour.
A ketogenic diet may also be:
- high in unhealthy saturated fats
- low in fibre, which can affect heart health, some chronic diseases and bowel problems, increasing the risk of bowel cancer
- missing important vitamins such as thiamine (vitamin B1), folate, vitamins A, E and B6, calcium, magnesium, iron and potassium
What are the side effects of a ketogenic diet?
Some of the possible negative effects of a keto diet include:
- bad breath
- feeling sick
- bowel problems
- high cholesterol
- kidney problems
- osteoporosis due to lack of calcium
- rapid weight gain when normal diet resumes
It is important to remember that individuals have different needs, and there is no ‘one size fits all’ type of diet. Anyone starting a ketogenic diet should do so under clinical supervision, along with an accredited practising dietitian.
For more information
- Talk to your doctor.
- Find an accredited practising dietitian from the Dietitians Association of Australia, or call 1800 812 942.
- Call the healthdirect helpline to speak with a registered nurse on 1800 022 222.
- Visit Epilepsy Action Australia or call 1300 37 45 37.
- Visit Epilepsy Australia or call 1300 852 853.
Last reviewed: May 2018