Ketogenic diet

Can you tell me what the Ketogenic Diet is please?

The Ketogenic Diet is also known as a ‘very low carbohydrate diet’ (a). Less than 50g a day of carbohydrate b is eaten and therefore increased quantities of fat and protein are eaten. 

It was traditionally a medical diet and has been used by doctors since the 1920s to treat epilepsy a, medication is now more likely to be used.  This diet produces chemical ‘ketones’ or ‘ketone bodies’ which can have an anticonvulsant effect.

There are other diets that use the low carbohydrate principle; one of the well-known ones is the Dukan diet for weight loss and we’ll be discussing this further on.

Can you help me understand how the Ketogenic Diet works please?

Under normal conditions our bodies use glucose to produce energy; glucose is provided by carbohydrate foods such as bread, pasta, grains, fruit and vegetables.  With the ketogenic diet the body uses ketones to create energy instead.  They are produced from stored fat when there are low levels of carbohydrates.  Foods that provide fats include dairy, oils, avocados, meats, oily fish, nuts and seeds.

I’d like more of an explanation, what else can you tell me?

Let me give you a simplified explanation of the physiological process called ‘ketosis’.  Scientists say that the average human body needs 60-65g of glucose per day.  After a few days of less than 50g/day carbohydrates or a few days of fasting there is not enough stored glucose to process into energy for the body or central nervous system (CNS).  The CNS includes the brain and this system normally uses glucose, it cannot use fat and so has to use another energy source. In this situation the liver will convert fat (in the form of triglycerides) into fatty acids and ketones which can be used by the CNS (b).  

You’ve mentioned that epileptics and people wanting to lose weight may benefit from this type of diet; are there any other health conditions that may benefit?

Research has also been undertaken in other health areas including diabetes, polycystic ovary syndrome (PSOC), acne and neurological diseases (a), (such as Alzheimer’s disease)(b) and to help with risk factors for respiratory and cardiovascular disease.  Researchers are also investigating whether a ketogenic diet may be beneficial for managing cancer (a).  Cancer cell metabolism uses glucose, so a diet with less glucose may be beneficial.   

In the area of research for Type 2 Diabetes and insulin resistance the researchers suggest that sufferers are likely to see symptom improvements with a well formulated very-low-carbohydrate diet.  The reason is that there is less glucose being consumed and also the fact that insulin sensitivity improves (b).

Will I lose weight if I follow this diet?

Research reviews differ in their support of the diet with one review stating there is strong evidence of the benefit of ketogenic diets for weight loss (b) but other opinions are that duration is an influential factor (c). The BDA (British Dietetic Association) has criticised diets that restrict food groups and this has featured in the popular media where they stated that the author of the Dukan diet states it may cause lack of energy, constipation and bad breath (d).

The mechanism of how the diet works is not conclusive, it may be due to increase protein making people fuller for longer, due to decreased calories or that the process of ketosis may act as an appetite suppressant by affecting levels of the satiety hormones leptin and ghrelin (b). Other researchers have concluded that the reasons for weight loss may include reduced water retention, reduced appetite and less insulin release (c).

Is it right that some sports people are interested in the ketogenic diet or a low carbohydrate high fat diet? 

Sportspeople are always interested in ways to improve performance.  Traditionally, levels of carbohydrate are recognised to effect endurance performance and are recommended before, during and after certain types and levels of exercise (e).  Other experts argue that there has not been sufficient research into low carbohydrate diets (f) for endurance sports and they advocate a high fat diet. Other research considers the Inuit culture that consumes low carbohydrate diets without a detrimental effect on their performance (g). Research continues and a low carbohydrate, high fat diet has not been shown to affect performance (nor improve) in strength sports such as gymnastics (h). 

Individual’s needs, the sport’s needs, and the training period or competition period will all affect what type of diet is appropriate, with no one size fits all diet. 

Can you tell me more about the Dukan diet for weightloss?

The Dukan diet provide a list of 68 animal proteins that are eaten during the Attack Phase which lasts between 5 and 10 days.  These are accompanied with oat bran which provides the carbohydrate and fibre, along with 6 to 8 glasses of water to aid excretion i.  Your body starts to adjust to new eating habits and get used to the lack of carbohydrate, it’s likely that you will experience the most weight loss during this phase.

Cruise Phase

On the Cruise Phase you alternate protein only days with days of protein and selected vegetables (j).  Vegetables are a good source of vitamins and minerals and essential for maintaining our bodies systems so it’s important to nourish your body this way, choose a rainbow of colours (Red, orange, yellow, green...) to ensure that you’re getting the widest range of phytonutrients.  This phase is slower than the Attack phase but the intention is to give you maintainable weight loss and lifelong good habits.


The Consolidation Phase is when you can give yourself a pat on the back! You have achieved your target weight.  At this stage many people are at risk of undoing their good habits though, therefore this phase and the next one ensure that you continue to manage your weight.  The length of this phase is determined by how much weight you have lost, i.e. 5 days of this phase for each 1 lb lost.

In this phase you can re-introduce defined quantities of low sugar fruits, cheese and bread j, perhaps you’d like to try this recipe to make your own low carb, free-from bread.

Stabilisation Phase

The Stabilisation Phase provides a set of guidelines for life, and advocates one or two protein days a week to manage your weight, keeping active, and eating daily oatbranj.

During the stabilisation phase you may like to try this recipe for Almond Shortbread which uses high protein, low-carb almond flour.

What’s your viewpoint on the Ketogenic diet and the Dukan diet?

My view is that the evidence supports the fact that the ketogenic diet was used for the therapeutic treatment of epilepsy, so it seems plausible that ongoing research will reveal other therapeutic benefits especially as many health conditions benefit from reduced glucose levels.

The Dukan diet is designed to give a plan to support people wanting to lose weight and change their lifestyle. The four structured phases will suit some people, I like the fact that it has two phases to provide support after the weight target is increased.

I recommend a pre-phase of healthier eating to provide a range of nutrients that support for liver and digestive system. I would include nutritious non-starchy vegetables such as green leafy vegetables like kale or spinach, sulphurous foods such as garlic and onions and the use of herbs and spices.  I would recommend this alongside reducing sugar, caffeine and alcohol before moving onto any weight loss diet.  Many people report side effects from sugar and caffeine withdrawal so a gentle approach before starting the diet may be advisable. 

There are certain instances when I wouldn’t recommend the Dukan diet, its dominant in animal protein so not suitable for vegetarians or vegans. Anyone with medical issues, kidney issues or a family history or kidney disease (due to the protein content) is recommended to speak to their GP first.  Sportsmen and women may need more carbohydrate for energy, or for specific parts of their training or competition and other busy people may have similar needs.

About the author:

Joanne Hart of health & hart  is a Registered Nutritional Therapist with a First Class BSc in Nutritional Therapy. She is a Yoga Teacher, NLP (Neuro Linguistic Programming) Practitioner and Member of the Association for Coaching (MAC). 

Joanne works with professionals (busy executives and high flyers) and athletes (sportsmen and women of all levels) to help them as they’re releasing their potential, achieving optimum health and performance.  She works one-one, in groups and delivers corporate programmes and can be contacted at


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