When benefits turn harmful: researchers debunk myths surrounding popular diets.

Calorie Counting Method

This method can be quite complex due to the numerous formulas involved. All of them are not entirely accurate because of the different coefficients used to calculate a person's physical activity. Moreover, the calorie content of foods listed on product packaging does not always reflect reality, with discrepancies of about 20 percent possible.

— It is important to consider that the calorie content of raw and cooked foods can vary. After culinary processing, the energy value of food increases. For instance, a raw egg contains 47 kilocalories, while a boiled one has 74, and an omelet contains 100 kcal. One must also take into account the state of the intestinal microbiota, which affects the absorption rate of the product for each individual, as well as the condition of the product itself—its ripeness, growing location, and many other factors. Is it worth counting calories? This approach helps control the overall caloric intake and teaches one to plan their diet, says Ekaterina Bankovskaya, associate professor at the Chemical Technologies Department of Perm Polytechnic University, PhD in Pharmaceutical Sciences.

The daily caloric norm is individual and depends on age, gender, level of physical activity, metabolism, and specific goals (weight loss, weight maintenance, or gaining mass). General recommendations are: women—1800–2400 kcal, men—2200–3000 kcal. Accurate calculations can be done using online calculators or by consulting dietitians.

Low-Carbohydrate Diet

This dietary regimen is based on a significant reduction in carbohydrate intake to about 50 grams per day while increasing fat consumption. The main food items include: meat (often sausages, hot dogs, and lean meats), fish (fatty varieties like salmon), a large quantity of seafood, dairy products, vegetables, fruits, and various plant oils.

According to the expert, this type of diet helps lower blood sugar levels, improve well-being, and promote weight loss through metabolic changes. However, it is essential to remember that carbohydrates are the primary source of energy for the body. Therefore, when carbohydrate intake sharply decreases, insulin secretion also decreases, leading the body into a catabolic state, which releases energy.

— The human body cannot sustain this state for long. After that, ketone bodies, primarily represented by acetone, become the main energy source. As a result, a person loses weight, but only slightly. If the diet is stopped, weight will almost immediately return to its previous state and may even increase. If a person continues to adhere to the diet, their overall condition may begin to deteriorate: blood pH will rise, and the risk of various liver diseases will increase, says Ekaterina Bankovskaya.

A sudden withdrawal from carbohydrates can impair thyroid function, lower testosterone levels in men, and affect the levels of female sex hormones in women, leading to reduced reproductive function, menstrual cycle disruptions, decreased bone density, and potential anxiety and depression.

Keto Diet - Zero-Carb

The daily intake of this diet consists of up to 75 percent fats, up to 20 percent protein, and only five percent carbohydrates. Fruits, grains, legumes, and dairy products are excluded. Meat, bacon, and sausages are encouraged.

One of the positive effects of the keto diet is weight loss due to the reduction of fat tissue. This type of diet is particularly beneficial for people with excess weight caused by insulin resistance and metabolic syndrome. Among the possible reasons for the higher effectiveness of the keto diet in normalizing body weight are the following factors: decreased appetite due to high fat intake; increased resting metabolism, meaning the body is busy converting fatty acids into energy and maintaining normal body temperature. Moreover, the keto diet normalizes blood pressure and lipid metabolism, increasing levels of high-density lipoproteins ("good" cholesterol).

— Despite its advantages, one should not completely restrict carbohydrates. They include not only baked goods and sweets but also fruits and vegetables, which are sources of vitamins, microelements, and fiber. This diet should not be followed for more than two months for weight loss, with a subsequent transition to a more balanced diet. The keto diet has many side effects: dehydration, the development of kidney stones, constipation, muscle cramps, amenorrhea in women, and slowed growth in children. The only medical indications for this type of diet are neurodegenerative diseases, epilepsy, and Alzheimer's disease, states Ekaterina Bankovskaya, associate professor at the Chemical Technologies Department of Perm Polytechnic University, PhD in Pharmaceutical Sciences.

According to the expert, fat digestion occurs in the small intestine. Regular excessive consumption of high-calorie foods (rich in lipids and sugars) leads to increased nutrient absorption in the intestine and, consequently, to excessive accumulation of lipids in the liver, adipose tissue, skeletal muscles, and other organs.

Consuming food high in fats improves the permeability of epithelial cells in the intestine and disrupts the interaction between the local immune system of the intestinal mucosa and the microbiota, leading to local and systemic inflammation and dysbiosis.

Paleo Diet

The name of the diet is a shortening of the word "Paleolithic," which refers to the ancient world, specifically the period when humans did not know how to cultivate grains and domesticate animals. Adherents of this dietary type exclude all grains and legumes, dairy products, and most "modern" foods that contain dyes, sugar, salt, preservatives, sweeteners, and more from their daily diet. The diet should consist of 40 percent proteins, 40 percent fats, and 20 percent carbohydrates.

To replace the necessary nutrients, supporters of this diet attempt to use lean meats and fish, a large quantity of vegetables, fruits, various greens, berries, seeds, and nuts. At first glance, the paleo diet may seem healthy, proper, and organic. However, according to the expert, following this dietary regimen raises doubts.

— If we compare the time frames and consider the fact that there was no active brain activity and many diseases at that time, as scientists say, whereas today a person has to "work with their head" and try not to get infected with various viral, infectious, or parasitic diseases, the number of which has long exceeded thousands, one can conclude that in the modern world, the paleo diet is dangerous, as the human body experiences a constant lack of carbohydrates and protein deficiency. Additionally, this may impair cognitive function, and high protein intake may harm the kidneys, explains Ekaterina Bankovskaya.

Intermittent Fasting

Intermittent fasting is based on the principle of autophagy, in which cells recycle themselves in the absence of food. Most often, people who follow this diet abstain from food for 6, 8, 16, or 20 hours. This dietary regimen has recently gained popularity because it genuinely helps individuals lose weight and maintain good physical shape without regular workouts.

— This positive effect is based on the fact that during periods of fasting, the human body begins to use subcutaneous fat as an energy source, as well as influences visceral fat. Furthermore, fasting stimulates the production of growth hormone, thus renewing the body's cells much faster. Another benefit is the removal of unnecessary substances at the cellular level, which reduces the risks of developing diabetes, various cardiovascular and respiratory diseases, as well as oncological diseases, notes Ekaterina Bankovskaya.

Unfortunately, the negative side of the diet can lead to exhaustion. This process begins almost immediately when a person starts to refrain from eating for more than 6 hours. At such times, not only fat cells are consumed, but also the body's proteins, which particularly affects muscle activity. One of the most severe complications is anemia. Intermittent fasting is definitely prohibited for those with liver problems or gallbladder issues. For example, if a dieter has fatty liver disease, prolonged fasting periods may trigger a vegetative crisis, with symptoms including cold sweat, hand tremors, and acute hunger.

Gluten-Free Diet

This diet is gaining popularity worldwide, especially among young people. Celiac disease—a chronic condition characterized by damage to the intestinal mucosa by gluten, a plant protein found in grains (gluten allergy)—has been known for a long time. Products that do not contain grain protein have been specifically produced for such individuals.

According to the expert, gluten-free products contain a small amount of gluten, which should not exceed 20 mg/kg. For people with celiac disease, this norm is practically a limit, while for healthy individuals, it represents a significant deficiency. Gluten-free products are generally higher in fats and carbohydrates, but contain minimal fiber. This leads healthy people to obesity, constipation, vitamin B group deficiencies, iron deficiencies, and serious metabolic disorders.

Mediterranean Diet

This diet is considered one of the healthiest eating models as it exhibits anti-inflammatory, antioxidant, and anti-cancer effects. The scientific community is increasingly conducting research on the relationship between the Mediterranean diet and obesity. Many of these studies provide evidence that adherence to this type of diet is linked to a reduction in obesity levels and a decreased risk of non-communicable diet-related diseases—results of the modern lifestyle.

— Adherents of this diet consume cold-pressed olive oil, legumes, vegetables, fruits, cereals (mainly whole grain products), fish, small