The goal of following a diet low in carbohydrates, also known as a ketogenic diet, is to get the body to replace glucose with a higher proportion of fats and amino acids (proteins) as the main source of energy.
“This causes a state of physiological ketosis in the body. Ketosis means that when fewer carbohydrates are available, less insulin is required, which leads to a reduction in lipogenesis (storage of body fat) and, therefore, less fat accumulation ”, points out Alma Palau, president of the General Council of Official Associations of Dietitians-Nutritionists (Cgcodn).
The specialist explains that after approximately three days of fast or from a drastically reduced carbohydrate intake (less than 50 g / day), glucose stores become insufficient for both normal fat oxidation and supply to the central nervous system (CNS). In this sense, it states that “the CNS must find an alternative energy source that is obtained from the oxidation of fatty acids, but more ketone bodies are also produced in the blood. For this reason, in this type of diet, urine ketosis is monitored ”.
This type of diet has been around since the early 1990s when it was found to be effective in managing epilepsy In children. Recently, these diets have gained popularity for managing obesity, diabetes type 2 and cardiovascular risk factors in overweight people. “It is important to take into account that the proportions of macronutrients (carbohydrates, fats and proteins) are not the same in treating childhood epilepsy and obesity, even if the diet is given the same name, ”Palau clarifies.
In addition, the nutritionist details that to follow a ketogenic diet, carbohydrate consumption is restricted to 20 g net or less per day to ensure that the body enters ketosis. On the other hand, the proportion of macronutrients varies within the following ranges:
- 65-80% of calories from fat (30% in the Mediterranean diet).
- 20-25% of calories from protein (15% in the Mediterranean diet).
- 5-10% of calories from net carbs (55% in the Mediterranean diet).
The dietitian emphasizes that the diet requires constant monitoring by the professional (weekly sessions for three months and, later, monthly in a certain period of time).
Antonio Gómez, member of the Executive Board of the Official College of Dietitians-Nutritionists of the Valencian Community (CODiNuCoVa) adds that the key is whether the choice of food focuses on quality options and good raw materials. “Any eating pattern that focuses on amounts of macronutrients is likely to be made with both good food and poorer quality products,” says the expert.
For a diet in which fatty and protein foods prevail, Palau expresses the need to promote especially those that have a more heart-healthy fat profile:
- Blue Fish. Salmon, anchovy, sardine, tuna, herring, eel, bonito, horse mackerel, sea bass and mackerel, among others. Unlike other fish, such as swordfish, this selection does not produce an accumulation of methylmercury.
- Nuts. These foods are rich in vegetable proteins and fiber, in addition to providing healthy fats. In addition, among the benefits of its consumption, its contribution of vitamins also stands out.
- Seeds. Like nuts, seeds are also a source of protein and healthy fats. Also, most of them are rich in vitamin B and E, as well as calcium, match, iron Y potassium.
- Extra virgin olive oil. In line with the above, olive oil contains healthy and essential fats such as Omega-6 and Omega-3.
- Avocado. Within the group of good fats, its health benefits are multiple. It offers a high content of vitamins (B, E and C, especially) and antioxidants.
What people are not recommended a low carbohydrate diet?
As already mentioned above, this regimen is advisable, provided it is under medical supervision, for people suffering from obesity, type 2 diabetes or suffering from cardiovascular risk factors such as cholesterol, glycosylated hemoglobin, and elevated triglycerides associated with being overweight.
However, Gómez comments that, in the field of sport Nutrition, “People who do physical activity on a regular basis or seek to gain muscle mass, the fact of reducing or restricting carbohydrates can hinder performance in the medium or long term, as well as progression in their sport.”
For its part, Palau also advises against pregnant women follow this diet because of the potential risk of contributing to the child’s cognitive or functional deficits. “Ketone bodies cross the placenta during pregnancy and reach the same levels in the maternal circulation. Since the fetus depends on a constant supply of glucose and amino acids to support growth, it is not clear how high levels of ketones can affect normal brain development, but it is suspected that it must be highly dangerous, “warns the dietician.
Likewise, the specialist reveals that, among the frequent adverse effects of the ketogenic diet, are nausea, vomiting, constipation or diarrhea, halitosis, headache, general weakness, muscle cramps, and skin rash. At this point, Palau says that “there are no long-term studies because adherence to diet is practically unsustainable for more than two or three months while a low-fat diet can become a new eating style.
Is it effective for losing weight?
Palau claims a very low-carb ketogenic diet does not result in clinically important weight loss per year compared to a low-fat diet (hypocaloric).
Finally, the nutritionist acknowledges that “there is evidence that the ketogenic diet improves HDL-C (good cholesterol) levels and lowers triglycerides compared to a low-fat diet. However, LDL-C (bad cholesterol) levels also rise.