Cardiovascular diseases remain a leading cause of death in Czechia, despite a reduction in mortality over the past 30 years. However, the prevalence of cardiometabolic risk factors like obesity, prediabetes, and diabetes has remained stagnant. A strong inverse association exists between education level and obesity, with lower education levels linked to poorer cardiometabolic health. This study aimed to explore the potential mediating factors in this association, hypothesizing that lifestyle, socioeconomic, and mental health factors play a mediating role. Previous research suggests links between lower education and poor lifestyle choices, socioeconomic disadvantage, and mental health issues, all of which are known risk factors for increased adiposity. Furthermore, sex differences in adiposity and related factors needed to be considered. Women tend to have higher body fat percentages than men, and there are also differences in dietary patterns and responses to dietary recommendations between the sexes. Therefore, this large community-based sample of middle-aged Czech men and women investigated educational disparities in adiposity and the potential mediating roles of various factors, with a focus on potential sex differences in these mediating pathways. The primary hypothesis was that lifestyle factors, socioeconomic characteristics, and mental health factors would mediate the association between education and adiposity, with a broader range of mediators likely influencing women compared to men.

Numerous studies have established an inverse relationship between education level and obesity across various populations and high-income countries. Lower education levels have consistently been associated with poorer lifestyle choices, including unhealthy diets, increased alcohol consumption, smoking, and sedentary behaviors. Socioeconomic disadvantage, including lower income, is also strongly associated with lower education levels and contributes to obesity risk. Additionally, research points to a significant association between lower education and poorer mental health, including higher rates of stress and depression, which are also linked to increased adiposity. However, existing literature lacks a comprehensive examination of the combined mediating effects of these factors on the education-adiposity relationship, particularly with a focus on sex-specific differences. This study aims to fill this gap by analyzing these diverse factors simultaneously, examining their independent and combined influences on adiposity across different education levels in both men and women.

This cross-sectional study used data from the Kardiovize study, a population-based sample of 2,154 adults aged 25-64 from Brno, Czechia. Participants were randomly selected and stratified by age and sex. Data collection involved in-person health interviews conducted by trained professionals, encompassing demographic information, socioeconomic factors, cardiovascular risk behaviors, smoking status, medical history, and mental health assessments. Anthropometric measurements, including height, weight, waist circumference, and body composition analysis (using bioelectrical impedance), were also collected. Education was categorized into three levels: high (higher professional or university education), middle (high school), and low (elementary or vocational education without a final graduation exam). Adiposity was assessed as a latent variable constructed from body fat percentage, BMI, waist circumference, and visceral fat. Potential mediating variables included dietary risk (a composite score based on several unhealthy dietary patterns), alcohol intake (grams of ethanol consumed weekly), smoking status (current, former, never), sedentary behavior (minutes per week), equivalized household income, stress (Cohen Perceived Stress Scale), depression (Patient Health Questionnaire-9), and quality of life. Data analysis was performed using STATA and MPlus software, with separate analyses conducted for men and women. Multiple mediation models were constructed to assess the indirect effects of education on adiposity through the potential mediators, using bootstrapping procedures to determine the significance of indirect effects. Confirmatory Factor Analysis (CFA) was used to confirm the unidimensionality of the latent adiposity factor.

The study found a statistically significant negative direct effect of education on adiposity in both men and women. In men, the indirect effect of education on adiposity was significantly mediated by sedentary behavior (β = 0.041; 95% CI [0.025–0.062]), accounting for 23.7% of the total effect. In women, the indirect effects were significant for dietary risk (β = −0.023, 95% CI [−0.037, −0.013]), alcohol intake (β = −0.006; 95% CI [−0.014, −0.001]), sedentary behavior (β = 0.012, 95% CI [0.004, 0.023]), income (β = −0.022; 95% CI [−0.041, −0.004]), and mental health (β = −0.007; 95% CI [−0.019, −0.001]), with a total mediation ratio of 30.5%. Multiple mediation models showed that higher education predicted decreased dietary risk and increased income in both sexes. However, the effect on smoking varied; higher education was associated with increased smoking in men but decreased smoking in women. While sedentary behavior showed a positive association with higher education in both sexes, its indirect effect on adiposity was in the opposite direction of the direct effect of education on adiposity, suggesting it might reduce the protective effect of higher education against adiposity. This effect was more pronounced in men (24.3%) than women (8.4%).

This study provides evidence that the association between education and adiposity is complex and differs by sex. In women, a combination of unhealthy dietary habits and lower income appear to contribute to the higher adiposity observed in those with lower education levels. In contrast, among men, the mediating role of the assessed factors was less clear-cut, with only sedentary behavior showing a significant indirect effect, although in an unexpected direction. The unexpected finding regarding sedentary behavior suggests that even though a higher educational level is protective, a higher prevalence of sedentary lifestyles among this group may counteract this protective effect. The fact that the investigated mediators only explained a portion of the total effect of education on adiposity suggests other significant factors might be involved, potentially including health literacy, self-management skills, and aspects of the social and physical environment. Future research should consider these additional factors to provide a more complete understanding of this complex relationship.

This study highlights the complex and sex-specific relationships between education and adiposity. While unhealthy diet and low income contribute to higher adiposity in less educated women, sedentary behavior appears to partially offset the protective effect of higher education in both sexes, particularly in men. This emphasizes the need for public health interventions to target sedentary lifestyles, especially in higher socioeconomic groups. Future research should broaden the scope of investigated mediators to fully understand this multifaceted relationship and inform effective prevention strategies.

This cross-sectional study design limits the ability to establish causality. The sample is city-based, limiting generalizability to urban populations. The reliance on self-reported data for several mediators introduces potential reporting bias. The dietary risk score, although constructed according to established guidelines, may not fully capture the complexity of dietary influences on adiposity. Lastly, while the study considered several important mediators, it did not explore all potential factors, such as health literacy, self-management, and environmental influences, which warrants further investigation.