Contribution of obesity in the association between fast-food consumption and depression: A mediation analysis

Background: Depression is a significant mental health concern, and the ubiquitous presence of fast-food in modern diets raises questions about its impact on mental well-being. Understanding the intricate relationship between fast-food consumption, obesity, and depression is essential for addressing the complex web of factors contributing to this public health issue. Methods: In this study, we analyzed data from the National Health and Nutritional Examination Surveys (NHANES) spanning from 2008 to 2018, involving 31,460 participants. Results: Among the 31,460 subjects in the survey, 2871 exhibited signs of depression, with an average age of 48.2 years. Each additional weekly fast-food meal was linked to 4 % higher odds of depression, with consuming over two such meals increasing the odds by 24 %. Adjusted models exploring the relationship between body mass index (BMI), fast-food consumption, and depression indicated an increased risk with greater fast-food intake, especially within subgroups based on obesity status. Mediation analysis revealed that fast-food consumption and depression were largely independent of obesity, with obesity accounting for only 6.5 % of the total effect. No significant mediation effect was found in the overweight subgroup, but the mediated effect was increased with higher BMI in more obese patients, notably in those with BMI >= 30 or >= 40. Sensitivity analysis confirmed these findings with more conservative estimates across all subgroups. Conclusion: This study highlights a substantial connection between fast-food consumption and depression. While obesity plays a role, it does not fully mediate the relationship, suggesting the presence of other contributing factors.