• very low in carbohydrates. You are limited to 20-50grams of carbohydrates per day
• moderate in protein
• high in fat. Your body will use fat as it’s primary energy source

As the ketogenic diet limits your carbohydrate intake to 20-50g of carbohydrates per day (equivalent to ~two slices of bread + a banana), your body needs to rely on fat as it’s primary source of energy. When your body metabolises (ie breaks down) fat for energy, it produces by-products called ketones. These are molecules made from fatty acids that build up in your blood stream and are used up by your muscles, brain & body tissue for energy. This process is called ketosis. 

Your body can enter ketosis during times of severe energy restriction, such as a fast or starvation, during prolonged intense exercise, or when your carbohydrate intake is reduced to less than 50g, such as the ketogenic diet.

Evidence For The Ketogenic Diet

Research supports a use of the ketogenic diet as medical nutrition therapy for some cases of epilepsy in children, as it has been found to reduce frequency and severity of seizures.

There is also growing interest in the effect of the ketogenic diet in patients with cancer, as tumour cells rely on glucose and can’t use ketones effectively. Much of the current evidence is observational, undertaken in small populations and in animals, so further research is needed before strong conclusions can be drawn.

There is limited scientific evidence for health benefits for the use of the ketogenic diet in healthy individuals.

Will The Ketogenic Diet Help Me Lose Weight?

Following a ketogenic diet most likely result in short-term weight loss. This is due to a number of factors including:

• a reduction in total energy (kilojoule) intake
• the depletion of liver & muscle glycogen stores
• reduced water weight (water is stored with carbohydrates in our body, so when you deplete your glycogen stores, you lose water weight too).
• reduced appetite – which is a side-effect of metabolising ketones, as well as the satiety associated with eating foods containing fat and protein.

While following a ketogenic diet will result in short term weight loss, the goal with most weight loss plans is to maintain the weight loss long term. It can be difficult to maintain a strict ketogenic diet & resulting weight loss over a long period of time, as the ketogenic diet drastically reduces your intake of a number of food groups including fruit and vegetables, dairy & grains. This means carbohydrate-containing foods, such as starchy vegetables, fruit, breads, cereals, rice, pasta & legumes must all be limited. There are also serious health risks associated with following a ketogenic diet long term.

Risks of Following The Ketogenic Diet 

Following a strict ketogenic diet can have serious health consequences. The short-term side effects of following a ketogenic diet include:

• fatigue
• headaches
• bad breath
• nausea
• constipation
• dehydration
• bowel problems

The long-term health risks of a strict ketogenic diet include:

• Nutrient deficiencies – the strict requirements to limit certain foods in the ketogenic diet makes it difficult to meet nutritional needs, which can result in nutrient deficiencies leading to conditions such as osteopenia & osteoporosis. If you choose to follow a ketogenic diet, supplementation is recommended.
• Compromised Gastrointestinal Health – with limited carbohydrates, the ketogenic diet is very low in fibre. This can cause gastrointestinal problems like constipation & increase your risk of bowel cancer. It also compromises the growth of healthy bacteria  in your gut, which can effect everything from your gut health, to your brain health & immune system.
• Other Health Problems – there are many other health problems that may result fro following a ketogenic diet long term including kidney problems, high cholesterol effecting heart health and numerous chronic diseases.
• Mental Health – with such a restrictive nature, following a ketogenic diet can impact on your social and mental health.

Take Home Message

While the ketogenic diet may offer short term weight loss, you need to weigh this up against the potential health risks. A ketogenic diet isn’t recommended for the general population, as the long term efficacy and safety of the diet are unknown, having only been studied in the short-term.

If you choose to follow a ketogenic diet, I would recommend seeking the help of a Dietitian to assist you.