For consumers, among the most important sources of information related to nutrition are popular journals and magazines, including women’s and sports, but the diets presented there may lead to unhealthy weight-control behaviors. The aim of the study was to assess the nutritional value of regular and low-calorie diets presented in Polish women’s and sports magazines before and during COVID-19 pandemic. The study was based on two popular Polish magazines—one women’s magazine and one sports magazine, which regularly present various types of diets. The nutritional value of all the diets published from January 2014 to May 2022 was analyzed. The total number of included single-day menus was n = 119, while for analysis they were stratified based on: type of magazine (published in the women’s magazine n = 41 and in the sports magazine n = 78), year of publication (before the COVID-19 pandemic n = 78 and during n = 41), and type of diet (regular n = 61 and low-calorie n = 58). The analysis included the energy value and nutritional value. For the type of magazine, the diets published in the sports magazine were characterized by a higher intake of fat (p < 0.0001 for intake in grams and in % of energy) and calcium (p = 0.0330), whereas the diets published in the women’s magazine were characterized by a higher intake of carbohydrates (p = 0.0226 for intake in grams, and p = 0.0002 for intake in % of energy) and fiber (p = 0.0163). For the year of publication, the diets published during the COVID-19 pandemic were characterized by a higher intake of protein (p = 0.0166 for intake in grams), sodium (p = 0.0465), calcium (p < 0.0001), vitamin D (p = 0.0197), vitamin B6 (p = 0.0207), and vitamin B12 (p = 0.0277), whereas the diets published before the COVID-19 pandemic were characterized by a higher intake of carbohydrates (p = 0.0243 for intake in % of energy). For the type of diet, the regular diets were characterized by a higher energy value (p = 0.0020), as well as by a higher intake of fat (p = 0.0162 for intake in grams), carbohydrates (p = 0.0390 for intake in grams), mono- and oligosaccharides (p = 0.0084 for intake in % of energy), fiber (p < 0.0001), magnesium (p = 0.0323), iron (p = 0.0307), and vitamin B6 (p = 0.0204). The nutritional value of the diets presented in the Polish women’s and sports magazines was not justified by the type of magazine or type of diet, associated with the target group, which may cause the following of improperly balanced diets. However, the changes in the typical nutritional value of diets presented in the Polish women’s and sports magazines during the COVID-19 pandemic were justified by some specific needs for the prevention and treatment of COVID-19.

Introduction and purpose: There are many reasons why patients with specific health disorders, as well as people in good health, decide to follow special diets. Often their choice falls on dietary models that include limited carbohydrate intake. The most popular in this area are low-carbohydrate and high-protein diets, which have a significant impact on metabolism, making them of particular interest to people with excessive body weight.  State of knowledge: Low-carbohydrate diets include many dietary models of varying restrictiveness, with or without achieving a state of ketosis. The ketogenic diet has the most promising clinical results in terms of effects on carbohydrate and fat metabolism. Long-term studies are still too few and inconsistent, also regarding the effects on weight loss compared to traditional approach. High-protein diets also include a reduction in carbohydrate intake, but with a higher protein content. Observations on the effect of weight reduction and metabolic modification are inconsistent. The possible multi-directional negative health effects seem to be a strong argument against recommending this approach. Conclusion: The basis of any reduction diet must be a reduced energy supply. This can be achieved in a variety of ways, which are designed to facilitate its implementation by patients, as well as to have the most beneficial effect on their impaired metabolism. Diversions from the traditional approach may have beneficial effects, but may also contribute to other health problems. It is important to consider the patients' health status as a whole, and to ensure specialist follow-up when using described special diets, because of possible side effects and difficulties in properly balancing the diet. They can only be recommended in specific cases. The standard in the management of excessive body weight remains the traditional approach, the effects of which are well documented and do not represent risk factors for other conditions.