Objective  To investigate the association between obesity and dyslipidemia among adult residents in three counties (cities) of Sichuan Province, and to reveal the potential non-linear dose-response relationship between body mass index (BMI) and waist circumference (WC) and the risk of dyslipidemia, providing an empirical basis for developing precise weight management strategies.

Methods This study was conducted in Dujiangyan City, Pujiang County, and Jiange County of Sichuan Province. A multi-stage cluster random sampling method was used to select communities (townships), households, and participants within each county (city). The survey was conducted in 2023 and included 11561 permanent residents aged ≥18 years. A binary logistic regression model was used to analyze the association between different types of obesity and dyslipidemia. A restricted cubic spline (RCS) model was employed to explore the dose-response relationship between BMI, WC, and dyslipidemia, with the model's goodness of fit assessed by the AIC value.

Results  Among the study subjects, the prevalence of dyslipidemia was 29.07%, overweight was 33.50%, obesity was 11.95%, and abdominal obesity was 29.79%. Logistic regression analysis showed that, after adjusting for confounding factors, both obesity (odds ratio OR = 1.22, 95% CI: 1.05-1.42) and abdominal obesity (OR = 1.23, 95% CI: 1.11-1.36) were positively associated with dyslipidemia compared to individuals with normal weight. After stratification by gender, the association between abdominal obesity and dyslipidemia was more significant in females (OR = 1.36, 95% CI: 1.18-1.57). The RCS model further revealed that the relationship between BMI and dyslipidemia followed a J-shaped curve, with an inflection point at a BMI of 24.87 kg/m². The relationship between WC and dyslipidemia showed an S-shaped curve, with an inflection point at a WC of 86 cm. This indicates that the strength of the association changes non-linearly as the values of these indicators increase.

Conclusion  Among adult residents of three counties (or cities) in Sichuan Province, obesity and abdominal obesity are independently associated with dyslipidemia, and the association exhibits non-linearity and female specificity. Weight management strategies should focus on individuals with general and abdominal obesity, particularly females with abdominal obesity. The risk inflection points for BMI and WC should be used as key indicators for early intervention.