Poland and the World Trapped in Obesity: Causes, Implications, and Strategies for Prevention

Abstract

Obesity is one of the most pressing global public health challenges of the 21st century, affecting over a billion people worldwide. Poland, like many industrialized countries, is experiencing a rapid increase in obesity prevalence across all age groups. This review provides a comprehensive analysis of the obesity trends in Poland in relation to global patterns, emphasizing the complex interplay of dietary habits, physical inactivity, screen time, socioeconomic determinants, and gut microbiota composition. Special attention is given to the health and economic consequences of obesity and the inefficiencies in Poland’s public health response. The article also discusses novel research directions, including the role of hypothalamic BNC2 neurons and NK2R receptors in appetite regulation and energy expenditure, as well as the cellular heterogeneity of adipose tissue. These discoveries may open new avenues for personalized obesity therapies. The findings underscore the urgent need for coordinated, interdisciplinary strategies at the national and international levels to reduce the burden of obesity and improve long-term health outcomes.

1. Introduction

Obesity is defined as the excessive accumulation of body fat, leading to numerous organ-related complications and posing a health threat to individuals [1]. The diagnosis of obesity is made by measuring a person’s weight and height and calculating the body mass index (BMI) using the following formula: weight (kg)/height² (m²). The WHO defines adult obesity as a BMI greater than or equal to 30. For children, age must be considered when defining obesity. For children under 5 years old, obesity is defined as a weight-for-height greater than three standard deviations above the median of the WHO Child Growth Standards. For children aged 5–19 years, obesity is defined as greater than two standard deviations above the median of the WHO Growth Reference [1].

Obesity is a condition that occurs on an unprecedented scale, representing one of the most dangerous health and life threats.

In 2022, one in eight people worldwide lived with obesity. Obesity among adults globally has more than doubled since 1990. In 2022, 890 million adults (aged 18 and older) lived with obesity, accounting for approximately 16% of the global adult population. Another growing concern is childhood obesity. In 2022, 37 million children under 5 years old and 160 million children and adolescents aged 5–19 years lived with obesity. In 2022, over 9 million adults in Poland struggled with obesity [2]. In 2019, 18.5% of Polish adults had obesity, which represents an increase of 11.3 percentage points over three years compared to 2022 [3]. Studies conducted between 2018 and 2020 indicated that obesity among Polish children aged 7–9 years was 12%. It was more common among boys (14%) than girls (10%) [4]. Obesity in children and adults results from excessive calorie intake, genetic factors, environmental influences, and psychological factors.

A comparative analysis of epidemiological trends indicates that the situation in Poland reflects global patterns of increasing obesity prevalence while simultaneously revealing characteristics typical of industrialized nations. Between 1995 and 2005, Poland experienced a marked increase in obesity rates, and projections at the time suggested that by 2030, the condition could affect up to 37% of men and 31.4% of women [5]. Current epidemiological data largely support these forecasts [2].

In the international context, Poland ranks among the countries with a high and steadily growing proportion of individuals affected by obesity. In contrast, countries such as Japan maintain significantly lower obesity rates. This is attributable, at least in part, to enduring traditional dietary patterns that are rich in vegetables, fish, fermented foods, and dietary fiber, combined with relatively higher levels of daily physical activity. The Japanese diet promotes a beneficial gut microbiota profile, which is critical in regulating metabolic processes and preventing obesity [5].

In Poland, by contrast, the Western-style diet predominates—characterized by a high intake of ultra-processed foods, refined sugars, and saturated fats, along with insufficient consumption of fiber, vegetables, fruits, and fish. Such dietary patterns contribute to deteriorating nutritional quality, intestinal dysbiosis, and an elevated risk of metabolic disorders. These tendencies are consistent with broader nutritional transitions observed across industrialized societies [5,6].

At the same time, a key factor contributing to increased body weight, particularly among children, is the decline in physical activity combined with a more sedentary lifestyle. When coupled with inadequate dietary habits, this behavioral shift creates an environment that is highly conducive to the early onset and development of obesity [7].

This study aims to analyze the prevalence of obesity in Poland in the context of global trends and to discuss the key factors influencing its development, including lifestyle, environmental, psychological, and microbiome-related determinants. It also evaluates the effectiveness of current public health responses. The article presents data on obesity prevalence across different regions, its causes, health and economic consequences, and strategies for prevention and treatment. Particular attention is given to the situation in Poland, where obesity is increasing rapidly. The study highlights the need for interdisciplinary action at both the national and international levels to address this growing challenge.

2. Materials and Methods

The study’s narrative was based on available epidemiological data, reports from public health institutions, and scientific research findings on obesity in both Poland and worldwide. Comparative methods and data synthesis were applied to identify the key factors contributing to the increasing prevalence of obesity and its associated health consequences. Particular attention was given to risk factors such as diet, physical activity, gut microbiota, genetic predispositions, and environmental and psychological determinants.

The literature search was conducted between October 2024 and January 2025 using the following databases: Science Direct, Scopus, PubMed, Google Scholar, and Web of Science. The searches were conducted using individual keywords and their combinations. The following terms were used: adult/cancer/children/diet/food deserts/food marketing/genetic factors/gut microbiota/hormonal factors/hormones/marketing tactics/medications/mental health/microbiota/obesity/causes/consequences/factors/food deserts/parental obesity/physical activity/physical inactivity/Poland/prevention/risk/screen time/sedentary behavior/sleep duration/statistics/stress/treatment/ultra-processed food.

The study incorporated data from reports published by the World Health Organization (WHO) and national Polish institutions, including the Supreme Audit Office (SAO), the National Health Fund (NFZ), and the Polish Ministry of Health. Epidemiological data from large-scale research projects, such as the WHO European Childhood Obesity Surveillance Initiative (COSI WHO) and the MultiSport Index Report, were also considered.

The selection criteria included review and original articles (primarily peer-reviewed), documents from public health institutions and epidemiological reports, full-text sources available online or through institutional access, and materials addressing adult and pediatric populations.

3. Selected Factors Influencing Obesity

Obesity is a complex, multifactorial condition influenced by various factors, ranging from lifestyle choices to genetic predispositions. The key factors contributing to the development of obesity are summarized in

Table 1. Factors contributing to obesity.

Factors	Description
Physical activity	Physical activity impacts obesity by increasing energy expenditure, which helps to reduce body fat. Regular exercise promotes weight loss by increasing metabolism and improving energy balance. Additionally, physical activity increases muscle mass, which leads to a higher basal metabolic rate. Regular exercise also improves insulin sensitivity, preventing the accumulation of body fat [8].
Screen time	Time spent watching television and using devices such as computers or phones has been associated with adverse health effects in terms of the risk of obesity [9].
Diet	A diet based on highly processed foods, such as fast food, which is high in sugars, fats, and salt, while low in fiber and nutrients, promotes excessive calorie intake and can lead to metabolic disorders [10,11].
Sleep duration	Short sleep duration may lead to increased appetite, hormonal imbalances, and an elevated risk of developing obesity [12].
Stress	Stress and obesity are interconnected through numerous mutually interacting mechanisms involving cognitive processes, behavior, physiology, and biochemistry. Stress triggers the release of glucocorticoids, which increase appetite, and insulin, which promotes food intake and the development of obesity [13,14].
Unhealthy lifestyle or parental obesity	Parental obesity increases the risk of obesity in children, both due to genetic factors and the imitation of unhealthy habits [15,16].
School environment	An unbalanced food offering in schools, limited opportunities for physical activity, and lack of nutrition education may contribute to the development of obesity [17,18].
Socio-economic factors	Poverty and low socio-economic status cause a lack of access to healthy food and places for physical activity, which increases the risk of obesity [19].
Food deserts	Food deserts are areas with limited access to stores that offer healthy food. Restricted access to nutritious food affects diet and related health outcomes, including obesity [20].
Hormonal factors	In the lateral hypothalamus, second-order neurons that secrete melanin-concentrating hormones and orexins play a key role in regulating food intake. Hormonal imbalances can contribute to the development of obesity. Estrogens influence body weight regulation, which is why postmenopausal women are at a higher risk of obesity-related complications compared to younger women [21,22].
Gut microbiota	The composition of the gut microbiota can influence metabolism and fat storage. Bacteria belonging to the Firmicutes phylum may play a role in the relationship between gut microbiota diversity and weight gain [23,24].
Genetic factors	The inheritance of obesity is primarily polygenic, meaning that multiple genes contribute to the determination of this trait. If one parent is obese, the child’s risk of developing obesity increases 4- to 5-fold, and if both parents are affected, the risk rises to 13-fold [25]. However, it is essential to note that inheritance refers only to the predisposition to obesity rather than the direct development of the condition at conception [26]. Genetically determined syndromes, such as Down syndrome, Laurence-Moon–Bardet-Biedl syndrome, Prader-Willi syndrome, and Turner syndrome, may increase body fat accumulation [27].
Medications	Some medications, such as antidepressants, antipsychotics, beta-blockers, contraceptives, glucocorticoids, and insulin, may cause weight gain [28,29].

Among the factors listed in Table 1, particular attention is drawn to environmental factors, which significantly impact the shaping of dietary habits and physical activity levels and, consequently, on an individual’s health.

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3.1. Dietary Habits

One of the leading environmental factors influencing excessive food consumption is improper eating habits, which are often rooted in family dietary patterns. Parents pass on their eating habits (the quality and quantity of consumed foods) to their children. In this way, children conform to the dietary rules and customs in the household, which, in many cases, leads to the continuation of these habits into adulthood. From an early age, parents, wanting the best for their child’s development, offer a variety of treats to ensure the child “looks good”. This leads to a situation where the child’s stomach can accommodate more significant quantities of food, which can result in overeating at later stages of development [30].

The most significant determinant of obesity is the excess energy supplied to the body through food. The average Polish individual is unaware of their caloric needs and often consumes too many kilocalories, typically in carbohydrates with a high glycemic index. For the body to function correctly, three to five meals a day should be eaten at appropriate intervals and with a proper distribution of energy intake across these meals [31].

3.2. Physical Activity

Physical activity should play a key role in every person’s life, as it supports the proper functioning of the body. In the context of the increasing average life expectancy, it becomes essential to maintain good physical and mental health for as long as possible. The results of the latest, seventh edition of the MultiSport Index report 2024 [32] indicate that, in Poland, there is a large group of people who do not engage in any physical activity, avoid it, or plan to start exercising but cite excuses such as lack of time, fatigue, or excessive responsibilities. This phenomenon is captured by the term “sportcrastination”—a relatively new term for the well-known mechanism of voluntarily postponing physical activity despite being aware of its health benefits.

The World Health Organization (WHO) recommends that adults have 150 min of moderate-intensity, or 75 min of vigorous-intensity physical activity, or equivalent, per week [33]. The WHO also recommends that children, adolescents, and adults reduce the time spent in a sedentary position, particularly in front of screens, for recreational purposes [33].

The WHO warns that new data [34] indicate that nearly one-third (31%) of adults worldwide (1.8 billion people) did not reach the recommended levels of physical activity in 2022. These results reveal a concerning trend of physical inactivity among adults, which has increased by about five percentage points from 2010 to 2022. If this trend continues, it is estimated that, by 2030, the percentage of adults not engaging in physical activity will rise to 35%.

The cyclical survey on the physical activity levels of Polish residents conducted by the Ministry of Sport and Tourism showed (

Table 2. Percentage of Polish individuals aged 15–69 meeting the WHO physical activity standards [30] for leisure time (excluding walking) or regular cycling for transportation.

Year	Men (%)	Women (%)	Overall (%)	Literature Reference
2023	32.0	24.0	28.0	[35]
2022	31.5	22.5	26.7	[36]
2021	37.1	29.5	33.1	[37]

) that, in 2023, the percentage of Poles aged 15–69 who met the physical activity standards recommended by the World Health Organization for leisure time (excluding walking) was 28%. This represents an increase compared to 2022, when it was 26.7%. However, in 2021, this percentage was higher, reaching 33.1%. It is worth noting that men consistently achieved higher physical activity levels throughout the analyzed period than women. Despite the slight increase in 2023, compared to the 2021 data, Poles have a noticeable decline in physical activity levels.

According to the MultiSport Index 2024 report [32], 66% of Polish adults engage in physical activity at least once a month, while one in three Poles (34%) does not exercise at all. Analyzing physical activity levels between 2017 and 2024 shows an increase in exercise frequency among already active individuals, with 36% engaging in physical activity at least three times a week in 2024, compared to 30% in 2017. However, the percentage of inactive individuals has not changed significantly. Less than half of Polish adults have a chance to meet the WHO’s guidelines for moderate physical activity—43% exercise for less than 3 h a week. Compared to the global statistics, however, Poland is not performing poorly.

The analysis of physical activity across four generations of Poles presented in the MultiSport Index 2024 report reveals significant differences in engagement levels between generations. Generation Z and Millennials show higher levels of physical activity, while Generation X and Baby Boomers demonstrate considerably lower levels of regular exercise. Generation Z (born 1995–2012) stands out for the highest activity levels, with only 9% of individuals not engaging in physical activity even once a month. Dominant activities include running, cycling, and swimming. Among Millennials (1980–1994), 28% do not participate in any activity within a month. They primarily focus on cycling and walking, with health benefits and enjoyment being their main motivations. Generation X (1965–1980) and Baby Boomers (1946–1964) show less activity, with 42% of Generation X and 57% of Baby Boomers not engaging in any physical activity. For the older generations, the main motivations are health prevention and relaxation, while the primary barriers to activity are lack of time and health issues.

However, it is often the case that the only form of physical activity for children is physical education classes at school. There is also an increasing number of reports about the widespread practice of excusing children from these classes. According to the MultiSport Index 2024 report [32], 20% of Poles declare they did not enjoy physical education classes at school. Unfortunately, for some individuals, these lessons were a source of stress and did not provide a foundation for developing sports interests in adulthood.

According to the data contained in the report prepared by the WHO in 2024 [38], the physical activity level of Polish adolescents is similar to the European average yet remains alarmingly low. In 2021/2022, only 23% of Polish boys and 14% of girls met the WHO recommendations for daily physical activity (at least 60 min of moderate or vigorous physical activity daily).

Furthermore, a decline in physical activity with age was observed—29% of the 11-year-old boys and 18% of the girls were active, while among the 15-year-olds, these figures dropped to 18% for the boys and only 9% for the girls. Poland ranks at an average level in Europe, but the results are worse than those of Scandinavian countries, where youth physical activity levels are significantly higher. The highest level of physical activity in Europe was recorded in Serbia, where 49% of the 11-year-old boys met the WHO recommendations, and in Slovenia and Finland, where less than 10% of the 11-year-olds were inactive. The lowest levels of physical activity were reported in Italy and Lithuania, where less than 3% of the 15-year-old girls reported daily physical activity as recommended by the WHO. Compared to Canada and the United States, where the education system promotes sports and extracurricular activities, Poland performs worse, mainly due to limited access to sports infrastructure and issues with physical education exemptions. Studies also indicate that the family’s material status significantly influences the physical activity levels of adolescents—youth from wealthier families are more active than their peers from lower socio-economic backgrounds. In Poland, 15% of adolescents from affluent families were inactive, while among those from less wealthy families, this percentage reached 32% [38]. This relationship underscores the need for initiatives that support access to sports for children from poorer families.

3.3. Screen Time

In the era of new technologies, widespread access to television (including advertisements), and the increasing significance of the internet, particularly social media, it is becoming increasingly difficult to dedicate time to physical activity. A sedentary lifestyle significantly affects the changes occurring in the human body. Time spent in front of the television, computer, or phone is often associated with increased food consumption, most commonly unhealthy options such as fast food, sweets, and salty snacks [39].

This phenomenon arises not only from a lack of physical activity but also from the influence of media content. Television programming, including advertisements, promotes snacking and reinforces unhealthy eating habits. Studies have shown that food-related cues appear in television broadcasts an average of ten times per hour, with the promoted products most often being high-energy, low-nutrient snacks. Evidence from international research indicates that children exposed to television food advertising tend to consume up to twice the amount of low-nutrient foods, such as sweets, salty snacks, and sugary drinks, as compared to their peers who are not exposed. Though not specific to Polish children, these findings highlight a global pattern that is also reflected in national trends [40].

Although the exact mechanisms linking screen time to obesity are still a subject of ongoing research, it has been suggested that limiting screen time is essential in preventing and reducing obesity among young people [41,42,43].

Research conducted in Poland has shown that children aged 2–14 spend an average of 2.4 h per day in front of a television or computer screen, with 6.9% exceeding 5 h daily. Each additional hour of television viewing per week increases the risk of obesity in school-aged children by 3% [40].

There were 35.75 million internet users in Poland at the start of 2024, when internet penetration stood at 88.1 percent. Poland was home to 27.90 million social media users in January 2024, equating to 68.8 percent of the total population. Internet users in Poland decreased by 796 thousand (−2.2 percent) between January 2023 and January 2024. Social media users in Poland increased by 400 thousand (+1.5 percent) between early 2023 and the beginning of 2024. The number of social media users in Poland at the start of 2024 was equivalent to 68.8 percent of the total population. There were 24.80 million users aged 18 and above using social media in Poland at the start of 2024, which was equivalent to 74.7 percent of the total population aged 18 and above at that time. At that time, 50.4 percent of Poland’s social media users were female, while 49.6 percent were male [44].

Long hours spent on the internet, including on social media, contribute to a sedentary lifestyle, which is one of the key risk factors for obesity. In Poland, the average daily time spent using the internet is 6 h and 17 min, close to the global average [Figure 1]. In countries such as Brazil and South Africa, where users spend over 9 h online daily, a greater health risk is associated with limited physical activity.

Regarding social media usage, Poland ranks below the global average. Polish users spend 1 h and 54 min per day on social media, whereas globally, the average is 2 h and 23 min (Figure 2). In countries such as Kenya (3 h and 43 min) or Brazil (3 h and 37 min), social media plays a much more significant role in daily life.

3.4. Marketing

Another factor negatively influencing excessive weight gain is the well-known marketing strategies of the food industry. Everywhere, people are surrounded by advertisements for unhealthy food. Television is one of the most frequently used marketing channels, and children are often the primary target group for such advertisements [39,46]. Using cartoon characters, movie stars, and celebrities to promote unhealthy food is a form of manipulation. A child, seeing that their favorite character endorses a product, also desires to have it [47].

As for the impact of advertising on adults, it is common to offer attractive gadgets in a set, 2+1 promotions (where, if you buy two products, you get the third one for free), and contests with prizes. These methods aim to attract potential customers, encouraging them to purchase the advertised, often unhealthy, food products.

In social media, increasing attention is being paid to the impact of advertisements, especially those promoting fast food, on eating habits. Aesthetic photos, catchy slogans, and attractive promotions effectively capture attention, shaping consumer preferences, which may contribute to an increase in obesity, particularly among children and adolescents. Fast food ads increase consumption, especially among children who regularly watch such advertisements. These children are more likely to ask their parents to purchase fast food products, which leads to more frequent consumption and, in combination with screen time, correlates with higher BMI scores [48].

Fast food producers invest in sponsorships and product placements in films and television programs. An essential element of their strategy is color psychology; brands often use red and yellow, which stimulate appetite and evoke positive emotions [46,48].

In July 2023, the World Health Organization (WHO) published updated policies for protecting children from the harmful effects of food marketing [49]. The recommendations regarding food marketing to children were first published by the WHO in 2010 [50]. These guidelines aim to reduce children’s exposure to advertisements for food products that are high in fats, sugars, and salt, which may contribute to the development of obesity and other diet-related diseases. The WHO recommends the introduction of strict regulations regarding food marketing, covering both traditional media and modern digital platforms, including social media, which are becoming increasingly popular among younger age groups. The document also emphasizes the need to promote healthy eating habits through education for children, parents, and caregivers and the implementation of public policies supporting a healthy diet. The WHO highlights the need to raise awareness about the impact of marketing on children’s food choices to protect their health and prevent long-term health consequences associated with an unhealthy diet.

3.5. Sleep Duration

Among the environmental factors that influence body weight gain is sleep duration [51,52].

Inadequate sleep duration (less than 6 h or more than 8 h) increases the risk of choosing foods with a high energy density more frequently [53]. Both short sleep, typically defined as less than 6 h per night, and excessive sleep can negatively impact body weight, increasing the risk of becoming overweight and of obesity in adults [54]. Similar relationships were observed in a study conducted on a group of 422 Caucasian children aged 5–10 years, as part of the “Québec en Forme” project [55], which found that both insufficient and excessive sleep was significantly correlated with an increased risk of excessive body weight.

Short sleep, typically lasting less than 6 h per night, is associated with an increased risk of obesity. Sleep restriction leads to hormonal changes that may promote increased calorie intake and reduced energy expenditure, ultimately contributing to weight gain. Limited sleep causes an increase in ghrelin levels (the hunger hormone), which stimulates appetite, and a decrease in leptin levels (the satiety hormone), which inhibits appetite, potentially leading to increased food intake, particularly high-fat and high-carbohydrate foods. Short sleep can also lead to reduced insulin sensitivity and glucose intolerance, which favor fat accumulation. Individuals who sleep less than 6 h daily often experience fatigue and daytime sleepiness, reducing physical activity and resulting in lower energy expenditure. Additionally, insufficient sleep weakens immune function [54,56,57].

A study conducted between June 2020 and March 2021, involving 67,254 adults worldwide, showed that the average sleep duration was 7 h and 30 min per day. Females had significantly longer average sleep durations (mean difference = 0.37 h) than males. Compared to the recommended range of 7–9 h of sleep per night, 31% of adults in this sample had an average sleep duration outside of this range (i.e., <7 or >9 h per night). Among individuals aged 18–25, about 19% had sleep durations shorter or longer than recommended, while in the group of people aged 51 and older, this percentage increased to 35%. The lowest average sleep duration was recorded in Japan (7.1 h), while the highest was observed in Mexico and Finland (7.7 h). The average sleep duration in Poland was 7.5 h [51].

In 2023, Poles aged 15 and older had an average sleep duration of 8 h and 33 min per day. Women had an average sleep duration 13 min longer than men (8 h and 38 min vs. 8 h and 25 min) [58].

3.6. The Microbiome in Obesity

The intestinal microbiota plays a crucial role in regulating numerous physiological processes, including inflammatory responses, supporting the immune system, and maintaining the structure and function of the intestinal wall [59].

3.6.1. Determinants of Gut Microbiota Composition Relevant to Obesity

Due to the complexity of the gut ecosystem, it is difficult to define a uniform microbiota pattern for the entire population. Its composition is influenced by many factors such as diet, physical activity, circadian rhythm, stress, medication use (especially antibiotics), environment, seasonality, and contact with microorganisms present in the surroundings [60,61].

Lifestyle, which encompasses all these elements, significantly shapes the gut microbiota, influencing its diversity and metabolic functionality. A modern, urbanized lifestyle may significantly reduce this diversity [61].

Diet

In recent decades, the popularity of the Western diet, typical of highly industrialized countries, has increased. This diet is characterized by the high consumption of highly processed foods, including fast food, ready-to-eat products, sweet and salty snacks, and sugar-sweetened beverages. It typically contains large amounts of animal-derived protein and fat while being low in dietary fiber, vitamins, and minerals [62]. Numerous studies have confirmed that the Western diet leads to a reduction in beneficial bacteria from the genera Bifidobacterium and Eubacterium, as well as a decrease in total bacterial counts [63]. In the context of the Polish population, studies on gut microbiota have revealed a characteristic microbial profile among healthy adults following a Western diet. Although the composition and number of bacterial species were similar in women and men, significant differences were observed in the overall microbial structure of the gut. Women showed higher abundances of bacteria from the genus Akkermansia and the families Christensenellaceae and Ruminococcaceae, which may indicate a more stable and anti-inflammatory microbiota profile, promoting better regulation of metabolic processes such as lipid and glucose metabolism and potentially lowering the risk of metabolic diseases compared to men [64].

The proportion of people struggling with obesity is increasing across all age groups, primarily due to the easy availability and growing consumption of high-calorie fast food, as well as technological advancements that significantly reduce daily physical activity levels [65]. Diet plays a crucial role in the health of the gut microbiome; it is known that diets high in fats and carbohydrates—especially Western-style diets or those low in fiber—impair gut barrier function in mice, affecting the levels of bacterial metabolites entering the bloodstream [66]. In addition to directly influencing the diversity and composition of the gut microbiota, dietary components such as nutrients, phytochemicals, or antibiotics can interfere with the host–microbiome relationship, compromising the protective functions of the intestinal barrier. This results in dysbiosis, which leads to inflammatory processes and a reduction in microbial diversity [59,66,67].

According to the current evidence, a well-balanced diet that is rich in dietary fiber, polyphenols, and fermented plant-based foods, such as the Japanese or Mediterranean diets [68], promotes the growth of beneficial bacterial strains like Faecalibacterium prausnitzii and Bifidobacterium. These microbes support the production of short-chain fatty acids (SCFAs), which in turn help to maintain intestinal barrier integrity, suppress inflammatory responses, and positively influence the host’s energy and insulin metabolism [64,69].

In contrast to such dietary patterns, a nutrition model based on highly processed foods, which is characteristic of the Western diet, favors the proliferation of pro-inflammatory bacterial strains (e.g., Proteobacteria, Fusobacteria) and reduces microbial diversity in the gut, which may contribute to the development of chronic metabolic disorders and obesity [66,67].

Changes in the gut microbiota can occur within 24–48 h following dietary modification, although permanent transformations require long-term interventions [69]. However, the microbiota’s response to a specific diet depends on its baseline composition, highlighting the importance of a personalized approach [66,67].

Physical Activity and Psychophysiological Factors

Regular physical activity positively influences the gut microbiota composition, increasing the abundance of bacteria such as Akkermansia muciniphila. These microbes support intestinal barrier integrity and the metabolism of short-chain fatty acids, thereby contributing to improved overall metabolic health [61].

Modern lifestyle factors, such as disrupted circadian rhythms, insufficient sleep, and chronic stress, adversely affect the gut–brain axis, leading to microbial imbalance (dysbiosis) [61].

3.6.2. Mechanisms Linking Gut Microbiota to the Development of Obesity

An increasing body of research indicates a significant association between gut microbiota composition and the development of obesity [59,60,68,69].

Current research suggests that the gut microbiome may influence metabolic disorders through modifications of signaling molecules produced by bacteria, which interact with both nearby tissues and distant organs, including the brain, indicating the existence of the so-called gut–brain axis [70].

Dysbiosis can lead to impairment of the intestinal barrier and the associated gut-associated lymphoid tissue (GALT), resulting in the translocation of bacterial components—lipopolysaccharides (LPS)—which trigger inflammatory processes contributing to the development of insulin resistance [71]. Notably, the concentration of lipopolysaccharides crossing the intestinal mucosal barrier is higher in individuals with obesity [72]. Moreover, inflammatory signals generated by adipocytes can disrupt intestinal barrier function, facilitating pathogen translocation [73]. As a consequence, the chronic low-grade inflammation characteristic of obesity may be exacerbated by changes in the composition of the gut microbiota [74].

Despite the advances in research, the composition of the gut microbiota in individuals with obesity remains incompletely understood. Recent analyses have revealed significant differences between the microbiota of individuals with obesity and those with normal body weight. In obese individuals, an increased abundance of Firmicutes, Fusobacteria, Proteobacteria, and Lactobacillus has been observed, along with a decreased abundance of Bacteroidetes, Akkermansia muciniphila, Faecalibacterium prausnitzii, Lactobacillus plantarum, and Lactobacillus paracasei. Furthermore, an elevated Firmicutes/Bacteroidetes ratio appears to be associated with obesity, as also demonstrated in animal model studies [60].

3.6.3. Maternal and Early-Life Microbiota in the Development of Obesity

The maternal gut microbiota and its metabolites, particularly short-chain fatty acids (SCFAs), are essential in regulating maternal energy metabolism and shaping the neonatal immune system. Disruptions in the infant’s gut microbiota composition, resulting from a maternal high-fat diet during pregnancy, have been linked to an increased risk of developing obesity and chronic inflammatory diseases. Moreover, maternal obesity during lactation affects the composition of human milk microbiota, potentially leading to dysbiosis in infants and contributing to obesity later in life. Studies have shown that children with obesity exhibit reduced levels of Bacteroides and Bifidobacterium, which are key SCFA producers, as compared to children with normal weight [75].

An increasing number of studies indicate that mode of delivery (vaginal birth versus cesarean section) significantly affects the composition of the neonatal gut microbiota [76,77,78,79].

Cesarean section (CS) delivery disrupts the physiological process of microbial colonization, which may result in reduced colonization by protective bacteria and increased susceptibility to non-communicable diseases, including obesity [76,77,78].

Children born via cesarean section exhibit significantly lower levels of bacteria from the genera Bacteroides and Bifidobacterium, which are crucial for proper carbohydrate metabolism and immune development. This may result in the reduced ability to digest human milk oligosaccharides, thereby promoting the development of unfavorable gut microbiota and triggering metabolic consequences [76].

At the same time, it has been demonstrated that newborns delivered via cesarean section and breastfed by mothers with a so-called secretor phenotype (characterized by the production of α1-2 fucosylated compounds) show a higher abundance of Akkermansia muciniphila, a beneficial microorganism associated with the treatment of obesity and metabolic disorders [80]. The presence of Akkermansia has been linked to improved intestinal barrier function, reduction of inflammation, and beneficial effects on body weight [81]. Due to these properties, its use as a probiotic supporting digestive health is being explored [82].

In a study of children up to seven years of age, the composition of the gut microbiota in children with a normal body weight differed significantly from that of children with a predisposition to being overweight. Monitoring the gut microbiota and its changes may therefore serve as a tool for early diagnosis, prevention, and intervention in the treatment of overweight and obesity in children [83].

Although the mechanisms underlying host-microbiota interactions are complex and still not fully understood, a growing body of evidence suggests that improving gut microbial diversity may offer a promising therapeutic strategy for the treatment of obesity and type 2 diabetes [59]. With progress in various fields of medicine, obesity treatment—like that of other chronic conditions—is increasingly moving toward a personalized approach. In this context, modulation of the gut microbiota, use of prebiotics and probiotics tailored to individual needs, as well as fecal microbiota transplantation, may represent alternative therapeutic strategies in the management of obesity and its metabolic complications [59].

The gut microbiota plays a key role in the pathogenesis of obesity and lifestyle through its influence on microbial composition and function. Which can modulate the risk of developing this disease. Interventions to improve diet quality, increase physical activity, and restore gut microbial diversity may constitute the essential components of obesity prevention and treatment strategies.

4. Consequences of Obesity

Excessive body fat leads to various health complications [84,85,86,87,88]. Among the complications associated with obesity, the most prominent include the follwoing:

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Atherosclerosis—This condition involves the narrowing of arteries due to cholesterol buildup. It develops when organs such as the kidneys, heart, brain, and limbs are insufficiently supplied with blood and oxygen [89]. It is a disease that often does not show symptoms for a long time and progresses slowly, leading to oxygen deprivation in organs. An associated condition is ischemic heart disease, which results from inadequate blood and oxygen supply to the heart. This disease accounts for approximately 70–80% of deaths among individuals suffering from obesity [90].

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Type 2 Diabetes—Characterized by beta-cell dysfunction and reduced insulin sensitivity, this condition is associated with insulin resistance [91].

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Hypertension—This occurs when the measured systolic blood pressure is 140 mm Hg or higher and/or the diastolic blood pressure is 90 mm Hg or higher.

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Obstructive Sleep Apnea (OSA)—Individuals with this condition are predominantly obese, with about 70% of those diagnosed with OSA having obesity [92]. Sleep apnea is characterized by repeated episodes of breathing cessation lasting more than 10 s and daytime drowsiness and dysfunction in the cardiovascular and respiratory systems [93].

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Depression—This is observed especially among children and adolescents [94], and negative societal perceptions and poor self-esteem often cause this. Depression-related low mood contributes to further discouragement from physical activity [95].

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Binge Eating Disorder—This disorder is associated with very low self-esteem and exacerbates symptoms of depression. It involves uncontrolled food consumption, regardless of the amount or quality [96].

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Gastroesophageal Reflux Disease (GERD)—Changes in the anatomy and physiology of the esophagus due to obesity include a higher frequency of motility disorders, weakening of the lower esophageal sphincter, and increased intra-abdominal pressure [97].

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Kidney Stones—The risk of developing kidney stones is higher in obese individuals, partly due to changes in urine composition. Obese individuals tend to have higher concentrations of substances that promote stone formation, such as calcium and oxalates [98].

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Fertility Problems—In women, excessive body mass and abdominal fat increase the risk of menstrual irregularities, including reduced chances of ovulation [99].

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Severe COVID-19—Obese individuals are at higher risk of severe illness, hospitalization, and even death from COVID-19 [100,101]. Obesity is often associated with reduced lung capacity, decreased respiratory reserve, and increased airway resistance. This makes obese individuals more vulnerable to severe pneumonia and acute respiratory failure, which are common complications of COVID-19 [102].

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Cancer—Obesity is linked to the development of various types of cancer, including breast, kidneys, liver, colon, cervix, gallbladder, bladder, esophagus, pancreas, and thyroid [103]. Several mechanisms explain this risk, such as chronic inflammation, insulin resistance, hormonal changes (e.g., elevated insulin and estrogen levels), metabolic disorders, and changes in the gut microbiome (

Table 3. Relationship between obesity and risk of developing selected types of cancer.

Type of Cancer	Impact of Obesity
Colorectal Cancer	Increased risk, including through chronic inflammation, insulin resistance, and hormonal disturbances (e.g., elevated insulin levels) [104].
Postmenopausal Breast Cancer	Increased risk, including through elevated levels of estrogens produced by adipose tissue, chronic inflammation, and insulin resistance [105].
Endometrial cancer	Increased risk, including through elevated levels of estrogens, insulin resistance, and chronic inflammation [106].
Esophageal cancer	Increased risk, including through gastroesophageal reflux, visceral obesity, insulin resistance, and changes in the gut microbiome [107].
Liver cancer	Increased risk, including through non-alcoholic fatty liver disease (NAFLD), insulin resistance, and chronic inflammation [108].
Gallbladder cancer	Increased risk, including through gallstones, chronic inflammation, and metabolic disorders [109].
Stomach cancer	Increased risk, including through gastroesophageal reflux, abdominal obesity, and metabolic disorders [110].

). Obesity is often associated with chronic inflammation, which can contribute to DNA damage and initiate the development of cancer.

A predicted increase in cancer incidence across different regions of the world between 2022 and 2045 is presented in Figure 3 [111]. The data highlight significant regional variations in the expected growth rates for different cancer types, including breast, colorectal, corpus uteri, gallbladder, liver and intrahepatic bile ducts, esophagus, and stomach cancers—all of which are strongly associated with obesity.

Brazil, South Africa, and Asia show the highest increases in cancer incidence, particularly for gastrointestinal and hormone-related cancers. These trends are strongly correlated with rising obesity, sedentary behavior, and dietary shifts toward processed and high-fat foods. In countries such as Brazil and South Africa, where users spend over 9 h per day online (Figure 1), a notable rise in cancer rates, including colorectal, liver, and esophageal cancers—types strongly linked to obesity—can be observed (Figure 3). In Poland, the trend follows the broader European pattern, with colorectal cancer showing the highest predicted increase (~30%). Other cancer types, such as breast, liver, and stomach cancers, exhibit moderate growth. In Poland and Europe, where average internet usage is lower, the increase in cancer incidence is less pronounced. Japan stands as an outlier in this dataset, with negative or very low predicted growth for breast and corpus uteri cancers (Figure 3), likely reflecting successful preventive measures, healthy lifestyle habits, and an advanced healthcare system. Gallbladder, stomach, and colorectal cancers show only slight increases, supporting the idea that dietary habits, such as reduced meat consumption and a higher intake of fish and vegetables, play a protective role.

Obesity has become one of the leading health problems worldwide, having a significant impact on public health in various countries and regions. The rise in obesity rates in adult populations is strongly associated with an increased incidence of several serious diseases, including cardiovascular diseases, type 2 diabetes, and various cancers.

Table 4. Prevalence of obesity and associated health outcomes in selected countries and regions in 2022.

Country/Region	Obesity Among Adults (%)	Most Common Effects	Prevalence
USA	41.64 [112]	Cardiovascular diseases (heart attack, stroke, hypertension), type 2 diabetes.	Cardiovascular diseases: 29% of men and 25% of women with overweight, type 2 diabetes: 42.2% [113]
Australia	32.05 [112]	Cardiovascular diseases, type 2 diabetes, cancers.	Cardiovascular diseases: 10% in obese individuals vs. 4.3% in individuals with normal body weight, type 2 diabetes: women with obesity have a 12-times higher risk of developing type 2 diabetes, men with obesity have a 7-times higher risk [114].
Kanada	28.16 [112]	Cardiovascular diseases, type 2 diabetes.	Type 2 diabetes: 13.4% in obese individuals, hypertension: 29.5% in obese individuals, heart diseases: 6.0% in obese individuals [115].
China	16.40 [116]	Hypertension, type 2 diabetes, cardiovascular diseases (estimated data based on Asian trends).	Hypertension: 51%, type 2 diabetes: 14.1% in boys and 16.9% in girls with obesity [117].
United Kingdom	26.94 [116]	Cancer (colorectal cancer, breast cancer), type 2 diabetes.	Type 2 diabetes: 6.9% in obese individuals vs. 1.7% in individuals with normal body weight, colorectal cancer: 3 times higher likelihood of developing in obese individuals [118].
Europe	23.30 [119]	Cardiovascular diseases (heart attack, stroke, hypertension), type 2 diabetes, cancers (breast cancer, colorectal cancer).	Cancers: at least 200,000 new cases of cancer annually in Europe are caused by obesity [85], 35% of ischemic heart diseases and 55% of hypertension cases in adults, 80% of type 2 diabetes cases [120].
Poland	32.19 [116]	Cardiovascular diseases, type 2 diabetes, cancers (estimated data based on global trends).	Hypertension: 62% in obese individuals [121].

presents data on the prevalence of obesity in selected countries and regions in 2022 and the most common diseases associated with obesity in these populations.

5. New Research Directions in Obesity

Although obesity remains one of the significant health challenges of the 21st century, emerging discoveries are opening new avenues in the fight against its consequences.

A significant contribution to understanding the mechanisms regulating appetite and energy balance, as well as identifying new therapeutic opportunities for treating obesity and other metabolic disorders, comes from the discovery of a novel population of BNC2 neurons in the hypothalamus [122] and research into the neurokinin 2 receptor (NK2R) [123].

BNC2 neurons, which are directly activated by leptin (a hormone secreted primarily by adipocytes), play a critical role in suppressing hunger. Until recently, the prevailing model of appetite regulation focused mainly on two neuronal populations in the hypothalamic arcuate nucleus, the orexigenic AGRP/NPY neurons, which stimulate food intake, and the anorexigenic POMC neurons, which inhibit it. However, activating these neurons does not result in an immediate reduction in food consumption.

Recent studies suggest an additional mechanism in which BNC2 neurons act as regulators capable of rapidly suppressing appetite. It has been demonstrated that BNC2 neurons can inhibit the activity of AGRP/NPY neurons, which are typically activated during fasting to stimulate food-seeking behavior. The activation of BNC2 neurons leads to an immediate suppression of appetite, distinguishing them from POMC neurons. Moreover, studies in animal models have shown that deletion of leptin receptors in BNC2 neurons results in significantly increased food intake and the development of obesity, suggesting that these neurons’ functions are essential for maintaining energy homeostasis.

Due to their capacity for rapid and direct appetite suppression, pharmacological activation of BNC2 neurons may represent an effective strategy for treating obesity by enabling the precise control of energy homeostasis through the targeted modulation of key neurohormonal pathways.

Simultaneously, research on the neurokinin 2 receptor (NK2R) has demonstrated that its activation integrates two critical mechanisms—increased energy expenditure and appetite suppression. This dual approach may aid in restoring energy balance and improving metabolic function in individuals affected by obesity. A previous challenge in targeting NK2R therapeutically has been the short half-life and low specificity of its natural ligand, neurokinin A. Selective long-acting NK2R agonists have been developed to overcome these limitations, enabling once-weekly administration in humans [123].

An essential aspect of understanding adipose tissue’s role in metabolism, particularly in the context of obesity, is its cellular heterogeneity [124]. Current therapeutic strategies for obesity, such as pharmacotherapy and bariatric surgery, are applied universally without considering the individual differences in adipose tissue function. The creation of a transcriptional atlas [124] has enabled a detailed characterization of diverse adipose cell populations, contributing to a deeper understanding of their role in metabolic regulation and opening the door to more personalized therapeutic strategies tailored to an individual’s adipose tissue profile.

These discoveries—spanning both the neuronal mechanisms of appetite regulation and the cellular heterogeneity of adipose tissue—can potentially be transformative in obesity treatment. Integrating these findings into future clinical research holds the promise of developing more effective and precise therapeutic interventions, enabling long-term body weight management.

6. Obesity Among the Population of Poland

Obesity is a widespread civilization disease that is also prevalent in Poland. According to the report by the Sustainable Development Solutions Network [93], the obesity rate in Poland in 2019 among adults was 23.1%. In 2023, the Supreme Audit Office (SAO)—the highest state control authority in Poland overseeing the functioning of public administration and the management of public funds—presented a detailed report on obesity in adults in Poland for the year 2022 [2]. The report highlighted the scale of the problem and the effectiveness of state actions in preventing and treating diseases related to excessive body weight. The SAO showed that the number of people affected by obesity and the amounts spent on its treatment has been systematically increasing; according to its estimates, in 2022, more than 9 million adults in Poland struggled with obesity, and direct expenditures related to this disease reached 9 billion PLN.

The SAO report revealed that, during the period under control (2020–2022), the healthcare system did not provide comprehensive care for individuals at risk of or suffering from obesity and its complications. Existing solutions failed to allow patients to fully benefit from guaranteed services, primarily due to the growing number of patients and the increasing waiting time for consultations. Poland lacks a comprehensive action plan focused on educating, preventing, and treating individuals with excessive body weight. Between 2020 and 2022, the number of patients and healthcare services provided increased by nearly 50% due to obesity-related diseases.

The SAO report uncovered alarming data regarding the low level of health awareness and the lack of effective prevention and medical care for individuals with obesity. Research results showed that many patients were unaware of the severity of the problem, and the healthcare system did not provide effective prevention and support. Disturbing data indicated that more than half of people with obesity (53%) believed they had a normal body weight. This points to a significant issue with self-assessment and health awareness. Furthermore, nearly half (47.4%) of people with obesity were unaware that it could lead to serious diseases, such as diabetes or hypertension. This is undoubtedly related to the shockingly low level of financial resources allocated to health promotion activities aimed at preventing obesity and overweight, even though this problem generates significant costs for the healthcare system. The SAO report showed that primary care physicians rarely engaged in prevention; only 17.9% of patients were weighed once a year, and only 28.3% received advice on diet and physical activity. Obese patients were more often referred to diabetology (67.6%) and surgical (62.9%) clinics, suggesting that obesity is not effectively treated in its earlier stages, and patients only see specialists when serious complications arise.

7. Conclusions

Obesity is one of the key health challenges of the 21st century that requires immediate action. This issue affects millions of people worldwide, and Poland is among the countries where obesity is rising particularly rapidly. The key factors analyzed indicate that a lack of physical activity, the consumption of highly processed food and drink, and prolonged screen time contribute to the increase in people with excess body weight. Obesity in Poland is becoming an increasingly serious problem, and the SAO report demonstrates the urgent need for action at both the educational and systemic levels, as the healthcare system in Poland does not provide effective prevention and health education, often leaving individuals with obesity to fend for themselves.

To effectively combat obesity, it is crucial to implement preventive strategies at various levels. Health education should be prioritized through mandatory educational programs in schools focused on healthy eating and physical activity. Additionally, nutritional regulations are essential, including limiting unhealthy food marketing, especially among children. Health policies must be developed to support individuals at risk of obesity, offering access to dietitians and physical activity programs. There must also be investments in sports infrastructure and active lifestyle promotion. International cooperation is another essential element, as countries can exchange experiences regarding effective obesity prevention strategies while implementing global recommendations from the World Health Organization. Finally, the systematic monitoring of obesity levels in society and research into new prevention and treatment methods are crucial. A growing body of research indicates that the gut microbiota and discoveries related to appetite-regulating mechanisms are opening promising directions for developing personalized obesity treatment.

Failure to take immediate action will lead to a further increase in the number of people with obesity, which will strain healthcare systems and economies worldwide. Poland and other countries must adopt a more decisive and comprehensive approach to combat the obesity epidemic to curb its growth and improve the quality of life for future generations.