Ketogenic diet

What is the ketogenic diet?

A ketogenic (or ‘keto’) diet is a low-carbohydrate, high-fat diet. While it has benefits as a medical treatment for certain groups of people, there is little evidence to support it as a long-term weight loss diet.

When you are on a ketogenic diet, you eat a very small amount of carbohydrates, some protein and a high amount of fat every day. Your body breaks down fat into ‘ketone bodies’ (or ‘ketones’) as energy through a process called ketosis. Some parts of your body, such as the brain and red blood cells, need glucose to work and can’t use ketones for energy. The body will break down proteins from food or your muscle to make glucose.

What do you eat on the ketogenic diet?

On a ketogenic diet you usually eat only 20g to 50g of carbohydrates per day. As an example, 50g of carbohydrate is equal to 2 slices of bread and a banana. Carbohydrates make up about 10% of your daily intake in a ketogenic diet. This means your body breaks down fat for energy and stays in a state of ketosis.

What is a carbohydrate?

Carbohydrates, or ‘carbs’, are important nutrients. They are an excellent source of energy for the body and especially the brain. You need carbohydrates to avoid ketoacidosis — this is when ketone levels in your blood become dangerously high.

As well as energy, most foods that contain carbohydrates also give your body vitamins, minerals and fibre for good bowel health.

What should I expect on a ketogenic diet?

The main foods you will eat on a ketogenic diet include meat, fish, eggs, cheese, oils, cream, avocado and nuts. You may have some low carbohydrate vegetables, such as lettuce and cucumbers. On a typical ketogenic diet, you will have only small amounts of rice, pasta, fruit, grains, bread, beans and starchy vegetables such as peas and potatoes.

It can be hard for you to get all your daily recommended nutrients while following the ketogenic diet.

What are the effects of a ketogenic diet?

A ketogenic diet will usually lead to weight loss in the short term. This may be because the diet is high in fat which keeps you feeling full for longer.

There are some possible short-term negative effects of a keto diet, including:

• gastro intestinal side effects
• headache
• nausea
• bad breath
• dehydration

The ketogenic diet as a medical treatment

Epilepsy

The ketogenic diet can be helpful if your child has epilepsy and continues to have seizures while on antiepileptic medicines. Your child should only start a ketogenic diet if their neurologist recommends it, and with the support of a specialised dietitian. Your child will also need supplements to make sure they get all the vitamins and minerals their body needs.

Diabetes

If you have type 2 diabetes, a ketogenic diet may improve blood sugar management in the short term. However, the long-term effects are not known, and eating a high fat diet can increase your cholesterol levels.

Other conditions

There is no evidence that the ketogenic diet can treat or cure cancer. Speak to your doctor if you are thinking about a ketogenic diet for health reasons, as there are health risks, and the diet is not right for everyone.

The ketogenic diet for weight loss

The ketogenic diet is often promoted for weight loss in people with type 2 diabetes but research is not consistent. It can usually help in the first few months but the weight loss often doesn’t last. In overweight people without diabetes, short-term benefits have been seen but long-term effects need more research.

The ketogenic diet can be hard to maintain because it limits what foods you can eat. This means many people drop out of the diet. This can also contribute to unhealthy, ‘yo-yo’ dieting behaviour. The key to maintaining a healthy weight in the long-term is a healthy eating pattern that you can follow over time.

Risks of the ketogenic diet

Low carbohydrate diets such as the ketogenic diet can affect your child’s growth and should be avoided.

If you take insulin or certain medicines for your diabetes you may be at increased risk of having low blood sugar (hypoglycaemia) while following the ketogenic diet. There is a risk of diabetic ketoacidosis if you take certain medicines particularly the SGLT-2 inhibitors and follow the ketogenic diet.

It is also not recommended to follow the ketogenic diet if you:

• are pregnant or breastfeeding
• are at risk of an eating disorder
• have kidney disease

When should I speak to my doctor?

Always speak to your doctor before you start the ketogenic diet to make sure it is the right choice for you. They may refer you to a dietitian to make sure that you get enough nutrients in your diet.