The relationship between depressive symptoms and BMI: 2005–2018 NHANES data

Depression is one of the most common diseases in the world, and severe depression is the second leading cause of disability in the world. However, the relationship between depressive symptoms and body mass index (BMI) is still unclear. The purpose of this study was to explore the relationship between BMI and depressive symptoms.We conducted a cross-sectional study involving 35,407 participants, all data collected from NHANES 2005-2018. A multivariable logistic regression model was used to analyze the relationship between depressive symptoms (outcome variables) and BMI levels (independent variables). The Patient Health Questionnaire (PHQ-9) was the primary measure of depressive symptoms. We also performed sensitivity analyses, including multiple sensitivity analyses.After adjusting for covariates, the ORS (95 % CI) of depressive symptoms from the lowest to the highest levels of BMI were 1.14 (1.00-1.30), 1.00 (Reference), 1.19 (1.05-1.35) and 1.45 (1.29-1.64), respectively. However, stratified analysis and sensitivity analysis showed that there was no U-shaped relationship between non-Hispanic black race and depressive symptoms.Self-reporting questionnaire may lead to recall bias or reporting bias; Cross-sectional studies failed to verify causality.There is a U-shaped relationship between depression and BMI. However, no such relationship was found among non-Hispanic blacks. More researches are needed to confirm the relationship between weight and depression, as well as the causal relationship between them.