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On the keto diet? : Our nutritionist explains the pros and cons

This article has been written by our nutritionist Bennedetta, who will review top level the pros and cons of following a keto diet. We do not recommend considering this diet without speaking to your GP and with the support of a nutritionist or dietitian.

What is the Keto diet?

The ketogenic diet is a diet that involves the consumption of low amount of carbohydrates, moderate amount of protein and high amount of fats including both saturated and unsaturated fats. It consists of approximately 5% of carbohydrates, 70% of fats and 25% of protein.

Typical keto diet foods

When did the Keto diet start?

The diet has been used since 1920 for the treatment of epilepsy and today is proposed as a potential approach for inducing weight loss in overweight and obese patients. It can cause rapid weight loss alongside a short term reduction insulin levels. However, and this is why following a keto diet should never be considered without medical supervision as it also causes an increase in LDL cholesterol (bad cholesterol), due to the elevated consumption of fats.

How does a keto diet affect the body?

The mechanism of action of the ketogenic diet consists of the production of some substances called ketone bodies that are used as a source of energy instead of glucose. Glucose is always the preferred source of energy, however, due to a drastic reduction in carbohydrates, the body needs to find an alternative source of energy and this alternative source is represented by the ketone bodies which are acetoacetate, 3-hydroxybutyrate and acetone. It is interesting to note that compared to glucose, ketone bodies are able to produce a higher quantity of energy allowing the body to burn fat. Contrary to glucose, ketones that aren't used as a fuel source are not stored and are waste products. The kidneys filter them out of the blood, which are then excreted out from the body.

The benefits of a short term keto diet

Several studies have shown that the keto diet is suitable for rapid weight loss. On average, people lose 3 kg a week. A meta-analysis comparing low-fat vs low-carb diet shows that the low-carb diet provides 0.9 kg additional weight loss compared to the low-fat diet. There are also significant reduction in triglycerides, diastolic blood pressure, but an increase in LDL cholesterol which can impact your heart health.

The risks of a keto diet

A recent meta-analysis showed clear risks of following this diet, which should always be considered. A prolonged use of this diet can have adverse effects including an increased in LDL cholesterol. For this reason, the diet is recommended to those who need to lose weight but are healthy and do not have any specific health conditions such as kidney disease or high LDL cholesterol.

Furthermore, as most carbohydrate-rich foods contain fibre and essential micronutrients, a low-carb high-fat diet leads to a decrease of fibre intake and negatively impacts gut function and overall health. After following a keto diet, it is therefore imperative to supplement potential nutritional deficiencies and ensure that enough fibre is consumed.

keto recipe

The cons of a keto diet

Finally, another limitation of the keto diet is that it is very restrictive, you have to have a very strict balance of high fat to low carbohydrate ratio plus no alcohol can be consumed. Keto diets also causes reduced appetite which can lead to restricted calorie intake and consequently a lack of energy risking potential inadequate uptake of vitamins and minerals.

When you start the keto diet, the first few days your body will have prolonged headaches and weaknesses and flu like symptoms. After the first few days of keto, hunger levels decrease, as the body gets used to a high-fat diet that provides satiety.

Despite the limitations, the are also many benefits that the keto diet provides. It has been demonstrated that this diet improves insulin levels in pre-diabetic and diabetic patients, helps people with seizures, and could help with other medical conditions although further research is needed.

The reason why this high-fat, low-carbohydrate diet has shown to be effective in the treatment of epilepsy is attributed to the generation of the ketone bodies. They provide brain cells (neurons and astrocytes) with an energy source that is more efficient than glucose, resulting in beneficial metabolic changes, such as increasing adenosine levels that positively manage seizures.

This is not a long term solution.

Currently, the long-term effects of the diet on health are not known. However, as multiple studies have shown that the diet can cause nutritional deficiencies and increased LDL cholesterol, it is not recommended to embrace the diet for a long period of time.

On the other hand, embracing the diet for a short period of time results in rapid weight loss, reduction of insulin levels, serum hemoglobin A1c and improvement of energy metabolism.

If you are considering the keto diet and crucially your GP has given you the all clear, contact us and we can help you decide if its the best approach for your needs.


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Augustin, K; Khabbush, A; Williams, S; Eaton, S; Orford, M; Cross, J H; Heales, S J R; Walker, M C; Williams, R S B (2018). Mechanisms of action for the medium-chain triglyceride ketogenic diet in neurological and metabolic disorders. The Lancet Neurology, 17(1), 84–93.

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