The ketogenic diet (better known as the keto diet, abbreviation of its name in English, ketogenic, or, directly, keto) is one of the dietary guidelines that generates the most discussion. And not only among dietitians-nutritionists, their followers also enter into angry debates about whether or not it is advisable to include cereals or legumes in the usual menu.
In reality, it is a very restrictive variety of the low carbohydrate diet or low carb diet. Its effectiveness as slimming dietAt least in the short term, it is metabolically based on a extreme restriction of carbohydratesalmost completely eliminating some food groups.
It is usually prescribed to people who want to lose weight, although it has quite a few followers in the gym environment, where the most extreme go so far as to call carbohydrates almost ‘poison’. The controversy arises not because of whether or not weight is lost, but because of the possible risks that it can present to health if it is maintained for a long time.
This is how the ketogenic diet works
The ketogenic diet is one that Restrict the consumption of compressed carbohydrates, reducing it to a amount less than 50 grams per day, depending on the person. This means that foods rich in carbohydrates will not provide more than 80-160 kilocalories per day within the total energy count, that is, between 5 and 10% of the total calories. The rest is divided between fats (70 to 80%) and proteins (10 to 20%).
When the body starts to ingest this amount of carbohydrates, it produces more ketone bodies that end up in the blood. This process is known as ketosis and that is what gives its name to this diet. «A process that some people subjected to chronorestriction or intermittent fasting can also experience,» explains Alfredo Martínez, director of the Precision Nutrition and Cardiovascular Health Program at the IMDEA Food Institute, and Honorary Academic at the Spanish Academy of Nutrition and Dietetics.
Effects of the ketogenic diet: lose weight and be less hungry
One of its main effects and, without a doubt, the most attractive for people who want to lose weight, is its ability to lose weight quickly. Since there is a low or very low intake of carbohydrates, which are the usual fuel for producing energy, the body, which has already used up glucose and glycogen, has to resort to fat. Consequently, mobilize adipose massand in a short time there is a notable weight loss.
On the other hand, the ketogenic diet «induces, substantially and secondarily, a decrease of appetite, since fats and proteins are more satiating than carbohydrates. Furthermore, it has associated waste of watersince the increase in protein intake, although moderate, increases the need to eliminate urea,” adds Martínez.
Mechanisms behind weight loss on the ketogenic diet
Let’s pause for a moment on the mechanisms that explain the success of this diet for weight loss. The first is obvious: in the absence of glycogen, the body draws on fat reserves. In fact, an increase in caloric expenditure occurs due to the metabolic effects of converting fats and proteins into glucose. But what about glucose on a ketogenic diet? Yes, there are organs that absolutely need glucose for their functioning. This is the case of the brain, certain parts of the kidney and the formation of red blood cells. So, even if it is little, the body has to generate it. And that ‘manufacturing’ requires a significant caloric expenditure.
In addition, this diet produces an important satiating effect, due to its high fat content:
- Decrease in hormones that stimulate appetite, such as insulin and ghrelin, when low amounts of carbohydrates are consumed.
- The body’s main fuel source, ketone bodies also decrease hunger.
Can you follow a ketogenic diet forever?
Many people, encouraged by seeing how the scale rewards their effort, decide to prolong the application of the diet over time. However, they do not take into account that «These types of diets are not designed to be maintained for long periods of time«says the expert.
There are many questions that need to be answered at a scientific level, especially the long-term effects and the advantages of adhering to this diet over time. Some negative side effects of a long-term ketogenic diet have been suggested. Among them:
- increased risk of kidney stones
- increased risk of osteoporosis
- increased uric acid in the blood (a risk factor for gout)
Furthermore, there may appear possible nutrient deficiencies in the long term if a variety of recommended foods are not included in the ketogenic diet.
It is important not to focus solely on eating high-fat foods, but to include a daily variety of permitted meats, fish, vegetables, fruits, nuts and seeds to ensure adequate intake of fibre, B vitamins and minerals (iron, magnesium, zinc). . . Many of these nutrients are found in foods such as whole grains, which are restricted in this diet. The advice of a dietitian-nutritionist will be key to minimizing these possible nutrient deficiencies.
Now, «no physiological alterations important to health have been observed in people who maintain the ketogenic diet for only a few months,» says Martínez. Next, he places special emphasis on the fact that this type of diet «They must always be carried out under medical supervision and by a specialized dietitian-nutritionist.”.
Who can follow a ketogenic diet?
In principle, this type of eating pattern that leads to ketosis is Suitable for all types of people, except children and pregnant women. Added to this group are those with health problems related to the kidney function, as a sufficient acute or chronic kidney disease. It is easy to understand that the kidney, one of the organs most involved in the elimination of the metabolites of this diet, is one of the organs that can suffer the most adverse effects.
Likewise, this diet can cause metabolic ketoacidosis, a decrease in the body’s pH, so people with alterations in metabolic homeostasis They should not follow it at all.
Above all, personalized and supervised by a dietitian-nutritionist
Martínez remembers that the key for any diet to be healthy, and especially the ketogenic one, must be as personalized as possible and balanced in micronutrients. For this reason, his position is not directly opposed to the ketogenic diet: “I generally reject any type of diet that is not prescribed and supervised by qualified specialists. «You cannot generalize about the suitability or otherwise of the ketogenic diet, because not all people respond in the same way to the same eating pattern.»
Add that reducing carbohydrate consumption to less than 50 grams a day does not have the same effects on the body of a 40-year-old man who carries out moderate physical activity, or that of a 25-year-old woman with a sedentary life. . . Along the same lines, and following this line of argument, the expert opposes, for example, a child following a ketogenic diet, since «his body is in a stage of life in which he must grow.» .
Is a vegetarian diet compatible with a ketogenic diet?
The fact that this diet is based on reducing carbohydrate consumption to below 10% of the total calories in the diet makes it «complicated for a vegetarian person to follow a ketogenic diet. It is not impossible, but to do it in a way correct and without health risks, it is essential that it be implemented and supervised by a specialized dietician-nutritionist. Otherwise, certain important nutritional deficiencies could occur.»
This difficulty in reconciling the vegetarian and ketogenic diet extends to all diets. low carb (low carbohydrate diets), since the percentage of carbohydrates in this type of diet is also low. «These diets are based on the fact that carbohydrates provide at most around 25% of the total calories of the diet (between 50 and 150 grams of carbohydrates). However, these quantities and percentages must always be personalized. There is no a unique pattern,» he asserts.
Prohibited and allowed foods on a ketogenic menu
In the list of foods allowed on the keto diet, fatty and protein foods are prioritized, such as eggs, poultry, fish, shellfish, meat and nuts. Now, «a minimum of vegetables should also be included, controlling the proportion of carbohydrates,» adds the expert.
At the opposite pole, foods whose consumption is reduced to a minimum, we find cereals (breads, flours, pastas, rice…), legumes, tubers, fruits, sweets, and starchy vegetables such as pumpkin. . , carrot, corn, beet… The strictest also add nuts and seeds.
Other low-carb diets instead allow certain amounts of fruits, vegetables, and whole grains.
The entry The controversy over the ketogenic diet: pros and cons of the keto diet was first published in Nutriiendo.
Your article helped me a lot, is there any more related content? Thanks!
Thank you for your sharing. I am worried that I lack creative ideas. It is your article that makes me full of hope. Thank you. But, I have a question, can you help me?