The ketogenic diet provides about 800-1000 kilocalories per day (maximum 1300 kcal) and involves the consumption of the three main categories of food: fats, including cheeses, proteins and vegetables (from which the few permitted carbohydrates are obtained) .
As seen in the introductory chapter on Ketogenic diet, also known as the "keto diet", it consists of a strict diet that drastically reduces the intake of carbohydrates while providing high amounts of fat and protein. In particular, the macronutrients taken with the diet are unbalanced and are distributed in the following proportions: 70-75% of fat, 15-25% of proteins and maximum 5% of carbohydrates (Figure 1).
Fig. 1 - percentage of macronutrients in the ketogenic diet (https://www.melarossa.it/dieta/dimaggere/dieta-chetogenica/)
In this chapter we will see what benefits a ketogenic diet can bring and which foods are allowed, which are allowed in moderation and, instead, which are to be avoided.
Benefits of the ketogenic diet
Being a real medical protocol, the ketogenic diet is used in the treatment of some pathologies, with good results. As already explained in the paragraph on the origins of the diet, it has been mainly used in the treatment of childhood and adult drug-unresponsive epilepsy. Excellent results were also obtained for severe obesity in subjects with a Body Mass Index (BMI) greater than 30 or between 25 and 29. This diet is in fact more effective than other weight loss diets thanks to the powerful but gradual suppression of appetite. induced by ketosis. In a 24-week study, men on the keto regimen lost twice as much fat as those on a low-fat diet. The keto diet is also prescribed to patients who have to undergo bariatric or osteo-articular surgery where rapid weight loss is required.
A short-lived keto diet can be carried out by those with overweight associated with risk factors, cellulite, localized adiposity and weight gain due to menopause and after pregnancy (but not during breastfeeding). According to some researches, the ketogenic diet is also useful in the treatment of other diseases affecting the nervous system such as Parkinson's, Alzheimer's and Multiple Sclerosis thanks to the protective effect and the ability of ketones to reduce oxidative stress on neurons. . In fact, in these neurodegenerative pathologies, there is a reduction in the conduction of nerve impulses and a strong decrease in the neurotransmitters responsible for cell-cell communication. Ketones are able to reduce atrophy by allowing neurons to partially recover their functionality. Autism spectrum disorders (ASD) may also benefit from the ketogenic diet as they exhibit characteristics similar to epilepsy such as the manifestation of seizures following neuronal hyper-excitability. The ketone bodies intervene by reducing this overstimulation, improving the symptoms. Migraine is another condition for which good results have been obtained with a reduction in the frequency of disabling headaches. Diabetes is a chronic disease characterized by a lack of insulin, the hormone that controls blood sugar. In particular, type 2 diabetes occurs in adulthood, is not hereditary and is due to poor eating habits, overweight and obesity.
Several studies carried out on patients with type 2 diabetes have shown a significant reduction in blood sugar; on a 16-week diet, most patients decreased or stopped the dose of the drugs, losing an average of 8 kg of weight, with a reduction in waist size, blood pressure, triglyceride and glycated hemoglobin levels. These effects have also been observed in metabolic syndromes, often pre-diabetic conditions, characterized by a set of risk factors for cardiovascular diseases and in non-alcoholic fatty liver disease (known as "fatty liver" and often linked to high-calorie diets and type 2). The ketogenic diet is prescribed to improve the symptoms of glucose transporter 1 deficiency syndrome, a rare genetic disorder characterized by the deficiency of a protein (GLUT1), resulting in impaired glucose transport to the brain. Symptoms manifest shortly after birth with developmental delay, movement difficulties and epileptic seizures. Ketone bodies, unlike glucose, are able to reach the brain without having to be transported by the GLUT1 protein, thus causing a reduction in symptoms. The keto diet seems to have beneficial effects on polycystic ovary syndrome (PCOS) characterized by hormonal imbalances due to the presence of ovarian cysts with consequent metabolic and reproductive effects (irregular cycles, overweight, acne, alopecia, hirsutism and infertility). PCOS, like type 2 diabetes, is also characterized by deinstallation resistance. By following a ketogenic diet, many women have been able to lose weight and improve reproductive system function. In recent years, some experiments have observed that the ketogenic diet associated with anti-cancer therapies may help in some types of cancer as carbohydrate restriction lowers blood sugar and controls insulin by slowing tumor growth. This is particularly important in breast cancer and some aggressive brain tumors such as glioblastoma multiforme. Obviously this is not enough to block the progression of these complex pathologies, especially in the advanced or terminal stages, but it can certainly contribute to improving the quality of life.
Traumatic brain injuries, almost always caused by severe blows to the head (accidents, beatings, falls…), when they are not lethal, can have devastating effects on brain function, such as memory and personality. Since trauma-damaged neurons struggle to use sugar, starting the ketogenic diet shortly after trauma provides an alternative source of energy for the brain by improving motor function and speeding recovery. Lately this type of diet is applied to commercial weight loss programs in healthy and / or sports subjects but, even in this case, it is essential to be followed by a multidisciplinary team to manage the diet without risk to health. During physical activity, the ketone bodies become a more efficient substrate from an energy point of view, guaranteeing greater muscle work for the same oxygen consumed compared to carbohydrates, with an increase in performance. In fact, the keto diet provides athletes with the proteins necessary for muscle recovery after prolonged effort by activating metabolic pathways responsible for the repair and growth of muscle cells, with an antioxidant effect. In addition, this diet preserves the strength and integrity of the muscle mass.
Foods allowed in the ketogenic diet:
To prefer healthy ones or saturated, monounsaturated and some types of polyunsaturated (especially omega 3 and omega 6). These include condiments (olive oil, soybean, coconut, sesame, linseed and avocado), butter, including peanut butter, lard. Mayonnaise, herbs, unsweetened mustard and apple cider vinegar are also allowed among the toppings. Extra dark chocolate (90%) as well as bitter cocoa are allowed.
They can be obtained from eggs, meat and fish, but also from some plant foods. In any case, always choose the highest fat protein sources. The meat can be fresh (game, steaks and beef burgers, veal, chicken, pork, turkey…) but also preserved (cold cuts such as speck, ham, bacon, bresaola, smoked meat). In addition to fish such as trout, salmon, tuna, mackerel, herring, plaice, sardines and anchovies, crustaceans (shrimps, lobsters, scampi, mantis shrimp) are also allowed. During the diet it is also recommended to take protein supplements to support the muscles for the maintenance of a constant lean mass.
Milk proteins (Whey Protein) to counteract the destruction of proteins induced by the lack of carbohydrates (protein catabolism); Creatine to support muscle function (especially for those who play sports); Branched-chain amino acids (BCAAs) to prevent proteins from being used and destroyed in place of glucose for energy during training; Glutamine to favor the elimination of nitrogenous waste resulting from protein degradation; mineral salts to keep their blood concentration constant since little fruit and vegetables are allowed; L-carnitine to promote the use of fatty acids as a source of energy.
Taken through non-starchy fruits and vegetables with low sugar content, without exceeding 30-50 grams per day. This category includes green leafy vegetables such as chard, rocket, chicory, radicchio, fennel, crucifers (cauliflower, broccoli, cabbage ...), celery, cucumbers, courgettes, chives, radish, courgette flowers and leeks. Asparagus, eggplant, squash, mushrooms, tomatoes, peppers, green beans, bamboo shoots and soy contain slightly more carbohydrates but can be safely consumed. The most recommended fruits are avocado and coconut, which also contain a lot of fat.
Strictly sugar-free water, coffee and tea / herbal tea. It is recommended to drink at least two liters of water.
Foods allowed in moderation in the ketogenic diet:
Whole yogurt, fresh cheeses (mozzarella, stracchino, ricotta, cottage cheese ...) due to their sugar content should be consumed occasionally, preferring more fat, aged and hard cheeses, made with whole milk.
Medium starchy vegetables and legumes
Artichokes, carrots, beets, chickpeas, lentils, soy, edamame and legume-based products such as hummus, tofu and tempeh.
Chestnuts, various types of nuts, almonds, pistachios, sunflower seeds and pumpkin (including pumpkin). Red fruits and berries.
Condiments that do not raise blood sugar levels: unsweetened ketchup, sour cream, lemon juice, soy sauce, various pickles, stevia and erythritol.
Fruit and vegetable juices, mixed centrifuged.
Foods to avoid in the ketogenic diet:
Any type such as white and cane sugar, sweeteners such as fructose, dextrose, maltose and lactose, artificial sweeteners (aspartame, sucralose) maple syrup, carob, corn, caramel and agave syrup, honey.
Fruits, vegetables and cereals
Sugary fruit (grapes, bananas, apples, oranges and exotic fruits), potatoes, all cereals and cereal-based products: wheat, rice, quinoa, cous-cous, corn and then pasta, bread products, polenta.
Packaged products based on carbohydrates
Snacks, crackers, baked goods and breakfast, diet bars, soups and canned products, sweets.
Sweetened, carbonated, alcoholic drinks
Coca-Cola, Soda, orange soda, wine, beer, liqueurs, milk substitutes of vegetable origin (almond milk, coconut, rice, soy ...), fruit juices with added sugars.
There Figure 2 shows the breakdown of macronutrients in the pyramid of foods provided in the ketogenic diet.
Fig. 2 - Foods allowed and forbidden during the ketogenic diet (https://spmsf.unipv.it/attachments/article/135/manuale-famiglia.pdf)
When the ketogenic diet is not recommended
However, the ketogenic diet is not for everyone and there are contraindications for people suffering from diseases that involve an inability of the body to metabolize fatty acids such as: primitive carnitine deficiency, carnitine palmitoyltransferase I and II deficiency, carnitine translocatase deficiency, beta-oxidation, long and medium chain 3-hydroxyacyl-CoenzymeA deficiency, pyruvate carboxylase deficiency and porphyria 1 and 2. Since the formation of ketone bodies involves the liver and the excess of these substances is excreted in the urine , subjects suffering from hepatic and renal insufficiency must avoid this diet. Even those who have problems with kidney stones, gallbladder or who have undergone the removal of the latter cannot adopt this diet. Unlike type 2 diabetes, type 1 diabetes occurs early, is hereditary and not related to lifestyle as it is immune-based due to the presence of autoantibodies that destroy pancreatic cells. These patients are insulin dependent and the ketogenic diet could cause excessive hypoglycemia leading to severe hormonal imbalances. The ketogenic diet is also not recommended for those suffering from angina, heart failure, arrhythmias and recent myocardial infarction or previous stroke. It is also not suitable for those who have suffered or are suffering from eating and / or mental disorders and in cases of alcohol and drug addictions that require more complex approaches. Finally, it is to be avoided for pregnant and breastfeeding women due to renal overload and imbalance of macronutrients that would not allow a correct growth of the fetus; in this phase of life, in fact, the diet must not exclude any food group.
According to the Food and Nutrition Research Center (CREA) and the Veronesi Foundation, the drastic reduction of carbohydrates can lead to a lack of micronutrients, especially calcium, vitamins (especially D and those of group B), iron ...
Possible side effects of the ketogenic diet
The ketogenic diet is a therapy and therefore is not free from side effects that generally occur in the first few days following the body's adaptation to ketosis and which include:
- Headache: affects one third of patients and usually disappears after 72 hours.
- Acetonic breath for which we recommend the use of oral sprays, chewing gum without carbohydrates or drinking a little orange juice.
- Gastrointestinal disorders: nausea, vomiting, diarrhea, swollen belly, reflux.
- Loss of appetite or pangs of hunger with an exaggerated craving for sugary foods.
- Tiredness, weakness, exhaustion, muscle cramps, mental confusion, dizziness.
- Sleep disturbances and irritability.
If the diet is very hard, symptoms such as: hair loss, dry mouth, constipation (if fiber intake is inadequate), chills, hypokalemia (low potassium levels), osteopenia and a tendency to form kidney stones may occasionally occur. . Of course, these symptoms don't all come together. However, if more than one occurs together and you have the feeling of being influenced, we speak of keto-flu or, from the English, “keto flu”. The ketone flu occurs in most of those who start the diet but its intensity and duration vary from person to person based on previous eating habits and body adaptation: for the lucky few it lasts only a few hours while in the most cases range from 2 to 4 days. There are a few cases where it lasted for nearly two weeks. To counteract this symptomatology, nutritionists recommend taking B vitamins and electrolytes, together with adequate hydration which also includes the consumption of meat and vegetable broth to maintain high levels of mineral salts.