The diets generally recommended by nutritionists include carbohydrates as the main source of calories, followed by protein sources and finally fats, forming the famous food pyramid. However, depending on the purpose of each person, this diet may not be the most appropriate.
In ketogenic diets, the scheme is reversed, the energy source is mainly from fats, while carbohydrates are ingested in minimal amounts. Proteins should be consumed in moderate amounts. This balance leads to a change in how cells obtain energy in the body.
The scarcity in the supply of carbohydrates, forces the liver to break down the fat from food and adipose tissue into fatty acids and ketone bodies for energy, increasing the levels of the latter in the blood, hence the name ketogenic diet.
The ketogenic diet is very similar to the dukan diet since both focus on drastically reducing carbohydrate consumption. Such a reduction causes the body to enter a state called ketosis in which there is a large increase in the levels of ketone bodies in the body.
During ketosis, the body becomes much more efficient at burning fat for energy. According to a study published in 2003 in the journal Current Atherosclerosis Reports that analyzed data from several clinical studies on ketogenic diets, fat itself can be transformed into ketone in the liver and serve as energy for the brain and other organs.
In a ketogenic diet, there can also be significant reductions in blood sugar levels and insulin levels that help prevent fat accumulation and have benefits for overall metabolic health.
How does the ketogenic diet work in weight loss?
At the beginning of carbohydrate deprivation, the first mobilized energy store is glycogen, present in the liver. Glycogen is nothing more than a complex carbohydrate that can easily be broken down into glucose to be released into the blood. The decrease in blood sugar levels without replacement by food leads to the release of glucagon, the hormone that promotes glycogen breakdown.
When all glycogen is consumed, the body starts to seek energy in lipids, both from food and from adipose tissue. When fats are used as the main energy source, a favorable calorie balance (ingesting fewer calories than daily demand) leads to the burning of stocks, that is, the body starts to consume the fat present in the adipose tissue in order to achieve energy and the resulting effect is what most people want, the loss of that fat that bothers them, with preservation of lean mass. As already mentioned, this breakdown of fats leads to the formation of ketone bodies that will be used by cells to obtain energy, which will characterize the ketogenic or ketosis state in the body .
One question that may arise at this point is the following: even without the intake of carbohydrates, blood glucose can remain at adequate levels? Yes, otherwise there would be a lack of control and the possibility of occurrence of hypoglycemic crisis that can generate serious consequences. However, the liver is able to produce glucose from other compounds that are not carbohydrates such as lactate, glycerol (a constituent part of triglycerides, that is, fat) and amino acids, by a process called gluconeogenesis. Thus, even without the ingestion of a large amount of carbohydrates, blood glucose can be finely controlled by the body.
How does the ketogenic diet work in the treatment of epilepsy?
The success of this diet in inhibiting the occurrence of seizures in cases of epilepsy, is due to the fact that with the high concentrations of ketone bodies in the blood, the brain tissue starts to use them as an energy source instead of glucose. Because they are a more efficient fuel than glucose, ketone bodies would have a neuroprotective effect, keeping neurons more stable.
Research published in 2001 in the journal Pediatrics showed that the ketogenic diet was able to reduce seizure episodes in children with epilepsy. Another even more recent study published in 2013 in the Biomedical Journal suggests the ketogenic diet as an early treatment option for epilepsy.
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What are the benefits of the ketogenic diet?
Let us now understand the expected benefits of eating such a diet properly.
1) Burning fat becomes easier
In diets rich in carbohydrates, the main energy source comes from this macronutrient. All carbohydrates are broken down to glucose to be used in mitochondria, the cellular organelles responsible for the production of energy by generating ATP, the molecule that stores all the converted energy. This is the classic way of obtaining energy. An abundant supply of glucose guarantees the maintenance of this cycle and saves the burning of other sources, fats and proteins.
When the body enters a state of ketosis, the entire fat oxidation system to obtain energy becomes activated to guarantee the energy supply in the scarcity of carbohydrates, using fats as the main source, that is, the body prepares itself to burn the fat efficiently and this process becomes easier.
In addition, the ketogenic diet promotes a decrease in the levels of glucose and blood sugar, preventing new adipose tissues from being formed and stimulating the burning of existing fat stores in the body.
2) Saves muscle mass
The ketogenic diet is an excellent way to lose weight without compromising muscle mass. The result of this is the reduction of the body fat indexand muscle definition. With an adequate supply of proteins from food, that is, at least 1.5g of protein per kilogram of body mass per day, and with the abundance of ketone bodies in the bloodstream, the body does not need to break down the proteins of the muscles in amino acids to produce glucose, thus avoiding the catabolic state of lean mass. In addition, the amount of calories consumed must also be adequate, as in extremely low-calorie diets, the liver’s ability to metabolize fats may not be sufficient to provide the energy the body needs for all daily activities, which will invariably take you to seek energy from other sources, that is, from breaking down proteins.
3) Helps to lower insulin levels
The insulin is a hormone closely related to carbohydrate metabolism and induces the accumulation of glucose as fat, or high insulin levels lead to greater ease in accumulating fat and block breakage.
Insulin secretion is stimulated by elevated blood glucose with the absorption of carbohydrates from food. In a diet with a low carbohydrate consumption, insulin secretion occurs only at baseline levels and this further favors the oxidation of fat stored in adipose tissue. In addition, low levels of insulin favor the secretion of other substances beneficial to fat loss and maintenance of lean mass such as growth hormone.
For patients with type 1 diabetes, a ketogenic diet can help prevent episodes of hypoglycemia, reduce the rate of glycated hemoglobin and improve general health. In the case of type 2 diabetes, it is able to reduce insulin resistance, which is the main cause of the disease.
4) Helps control appetite
An important aspect of the ketogenic state is that, in addition to stimulating the breakdown of fats, it appears to inhibit appetite when associated with a high protein intake, while diets rich in carbohydrates only lead to an increase in appetite for triggering large variations and peaks of insulin. This will help in maintaining the diet, which is characterized by being in small portions, since fats have a high caloric density. Satiety, then, can be an obstacle for those who want to follow the ketogenic diet, but the good thing is that after conquering the high levels of ketones it becomes easier to overcome hunger.
Eating protein in a ketogenic diet helps to control your appetite, as proteins help keep you full longer. According to a study published in 2013 in the European Journal of Clinical Nutrition, the ketogenic diet alters the concentrations of various hormones that interfere with appetite and, thus, influence the amount of circulating ghrelin in the blood – hunger hormone.
When on a diet, it is common for ghrelin levels to rise because of recent weight loss, but in the ketogenic diet this is less observed, which suggests that the diet helps control appetite and improves weight loss results when compared to other weight loss plans.
What are the proportions of nutrients in a ketogenic diet?
It is important to note that a ketogenic diet is not a high protein diet, which is also widely used for weight loss purposes.
In the ketogenic diet, fats are the main energy source, accounting for about 60 to 70% of daily calories, while proteins must provide 30 to 40% of those calories and carbohydrates only 2 to 8%.
Even in ketogenic diets, small amounts of carbohydrate should be ingested, usually not exceeding 50g per day and at appropriate times, according to the plan made by your nutritionist.
As with any diet, over time it must be changed to continue inducing the body to react in different ways, maintaining an accelerated metabolism. So it usually starts with higher proportions of fats and less of proteins, and gradually the proportion of proteins increases. When weight loss occurs, it is also necessary to pay attention to the total amount of calories, people with less body mass, consume less calories. Otherwise, weight loss may stagnate.
Which menu should be followed in a ketogenic diet?
A ketogenic diet should be rich in eggs, meat, poultry, fish, nuts, healthy oils, avocado and vegetables with small percentages of carbohydrates. Drinks like coffee and tea should be sweetened with sweeteners, the most recommended being stevia. Escape from pasta, bread, cookies, sweets in general, processed foods, juices, fruits with a high sugar load, cereals and tubers rich in carbohydrates such as potatoes and manioc.