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The ketogenic diet: how it works and its benefits

The ketogenic or "keto" diet is attracting more and more followers thanks to its effectiveness for fat loss. What exactly does it consist of, what foods should be favored and what are its characteristics?
Le régime cétogène : son fonctionnement et ses bénéfices

The ketogenic or “keto” diet is attracting more and more followers thanks to its effectiveness for fat loss. What exactly does it consist of, which foods should we favor and what are its characteristics? 

Contents :

  • What is a ketogenic diet?
  • How does ketosis work?
  • The distribution of macronutrients
  • Meal Ideas for a Ketogenic Diet
  • Ketogenic diet and physical activity
  • What are the benefits of the ketogenic diet?
  • The side effects
  • What is a ketogenic diet?

    The ketogenic diet, also called “keto diet”, is a popular diet recommended for losing weight quickly. Unlike other diets, this one is based on a diet very low in carbohydrates and high in lipids. The objective is to reduce glycogen reserves, to the point of exhaustion, so that the body draws on accumulated fat as a source of energy.

    Originally, the ketogenic diet was recommended for certain health problems including epileptic seizures (1) and the side effects of heavy treatments. Its role in slimming diets and the treatment of overweight people was not defined until much later.

    How does ketosis work?

    The ketogenic diet allows you to enter a state of ketosis. This is a metabolic state achieved due to the lack of carbohydrates in the body. In order to produce energy intermediately, the body draws on fat reserves. When fatty acids break down, they are transformed into what are called ketone bodies. There are three types: acetoacetate, hydroxybutyrate and acetone.

    There are several ways to enter a state of ketosis: the first is of course to reduce your carbohydrate intake and increase your fatty acid intake. Normally, the recommended nutritional intakes are: 15% proteins, 45-50% carbohydrates and 35-40% lipids*. During a ketogenic diet, you can count 5 to 10% carbohydrates, 70 to 80% fats and 20 to 25% proteins.

    *data set by ANSES (the National Food Safety Agency) in 2019.

    The second way is to start your ketogenic diet by practicing a short-term fast which will allow you to empty your carbohydrate stores more easily. Fasting can also be intermittent, such as skipping a meal. However, this method may be more brutal for your body, so it is always advisable to consult a doctor before starting.

    Practice regular activity

    In order to maintain an effective state of ketosis, it is important to burn ingested carbohydrates. For this, regular physical activity is recommended. In addition, by remaining active, the body will be forced to use fat more easily to produce energy. Weight loss will be that much faster.

    Aim to exercise at a low intensity at least 30 minutes every day or three times a week at a high intensity.

    What are the benefits of the ketogenic diet?

    fat loss

    As seen previously, when your carbohydrate store is empty, your body will switch to burning fat to provide energy to the cells. This metabolic state allows weight loss through the rapid use of fats. This is why the ketogenic diet is used in the treatment of people who are overweight or obese (2,3).

    In addition, thanks to the cessation of carbohydrates, the ketogenic diet helps control blood sugar levels.

    Finally, the slimming action of the diet is also due to its richness in ketones in the body which would have effects on reducing appetite.

    Energy improvement

    Lipids, which constitute the main food source of the diet, provide a much higher level of energy than carbohydrates: there are 4 calories in 1 gram of carbohydrates and 9 calories in 1 gram of lipids. In addition, lipid stores are much less limited than those of glycogen stores.

    Two of the ketone bodies (acetoacetate and hydroxybutyrate) are considered real fuels for several organs, including the brain and heart.

    Thanks to the energy provided and the antioxidant activity of ketone bodies, the ketogenic diet has many benefits in neurological functioning. This is why its effects arouse the interest of researchers in the case of certain neurodegenerative diseases (4,5).

    The distribution of macronutrients

    We have seen previously that the distribution of macronutrients is very specific for a ketogenic diet. There are 5 to 10% carbohydrates, 70 to 80% lipids and 20 to 25% proteins.

    The proteins

    The protein level must be increased. For a person, there are 1 to 1.5g per kg of body weight. Here are some examples of protein sources:

  • Meat
  • Poultry
  • Seeds
  • Hard cheeses
  • Eggs
  • Tofu
  • Carbohydrates

    They should be avoided as much as possible in a ketogenic diet and gradually reintegrated into the diet. The level of carbohydrates should not exceed 10% of daily intake and come from specific sources. Here are some examples:

  • Yam
  • Rice
  • Quinoa
  • Oatmeal
  • Lipids

    Lipids in the form of good fats are the first nutrients to favor in order to practice a ketogenic diet. It is necessary to consume enough of it and on a regular basis in order to stay in a state of ketosis. The lipid level must be between 70 and 80% of the daily intake. The main sources of fats are obviously of plant origin: olive oil, coconut oil, seeds, nuts, etc. But there are also contributions from animal fats such as omega-3 and fatty fish. Here are other examples:

  • Meats, particularly beef;
  • High-fat, low-fat vegetables like avocado, cucumber, kale;
  • Eggs ;
  • The different dairy products (cream, butter, cheese)
  • The dried fruit
  • oily fish
  • Vegetable oils (coconut, olive, rapeseed or sesame)
  • Meal ideas for a ketogenic diet

    Typical menu during a ketogenic diet:

    Morning :

  • Scrambled eggs
  • Lawyer
  • Bacon (optional)
  • Noon :

  • Beef stuffed peppers
  • Greek yogurt
  • To taste :

  • A handful of oilseeds (walnuts, almonds, etc.)
  • Sugar-free tea
  • Or

  • Pancakes
  • Peanut or almond butter
  • Dinner

  • Risotto (cauliflower rice) with chicken and mushrooms
  • Foods to avoid:

  • Starches (pasta, potato, etc.)
  • Foods that are too sweet and/or processed (pastries, soda, candy, chocolate, etc.)
  • Some fruits and vegetables that are too sweet (except red berries)
  • The side effects

    Like any diet that restricts the consumption of certain foods, the ketogenic diet can be difficult to follow and can even cause certain disadvantages.

    Among these, the arrival of a more or less important fatigue according to the habits of personal lives of each one. Indeed, by eliminating a certain amount of nutrients from the diet, it is possible to feel a lack of vitamins, minerals and fiber. In this case, macronutrient supplementation may be an adequate solution.

    There is also a strong tendency to dehydration. It is therefore recommended to drink 2.5 liters a day, or even more during training days.

    Finally, the ketogenic diet is accompanied by a period known as “ketogenic flu”, where the body is in a state of ketosis. This can occur after the fifth day of the diet, up to two weeks later.

    Scientific references

  • P. Thesis: The ketogenic diet, a therapeutic alternative in drug-resistant epilepsies . 2014. Faculty of Pharmacy.
  • Basilio Moreno, Ana B Crujeiras, et al. Obesity treatment by very low-calorie-ketogenic diet at two years: reduction in visceral fat and on the burden of disease . Endocrine. 54, 681–690 (2016).
  • B, Ingrid S. et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomized controlled trials . Cambridge University Press. 2013
  • Dariusz Włodarek. Role of Ketogenic Diets in Neurodegenerative Diseases (Alzheimer's Disease and Parkinson's Disease) . Nutrients. 2019 Jan 15;11(1):169.
  • Prins ML, Matsumoto JH The collective therapeutic potential of cerebral ketone metabolism in traumatic brain injury . J. Lipid Res. 2014;55:2450–2457. doi: 10.1194/jlr.R046706.

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