Residual Atherogenic Dyslipidemia in Normal-Weight Adults: The Role of Visceral Adiposity and Metabolic Dysfunction

Background. Body mass index (BMI) remains the most widely used tool for obesity classification and cardiometabolic risk stratification. However, increasing evidence suggests that normal BMI does not necessarily reflect metabolic health, particularly in individuals with hidden visceral adiposity and residual atherogenic dyslipidemia. The present study aimed to evaluate the prevalence of residual atherogenic dyslipidemia among normal-weight adults and to analyze its association with visceral adiposity, metabolic dysfunction, and lifestyle-related factors. Methods. A cross-sectional observational study was conducted in 166,008 Spanish workers aged 18–69 years with normal BMI (18.5–24.9 kg/m2) who underwent standardized occupational health examinations between 2022 and 2024. Anthropometric, biochemical, vascular, and lifestyle-related variables were evaluated. Visceral adiposity was estimated using waist-to-height ratio (WtHR) and the Metabolic Score for Visceral Fat (METS-VF). Residual atherogenic dyslipidemia was primarily assessed using the triglyceride-to-HDL cholesterol ratio (TG/HDL-c). Multivariable logistic regression analyses were performed to identify independent associations with elevated TG/HDL-c. Results. Despite normal BMI values, 8.0% of participants presented with an elevated TG/HDL-c ratio, 11.8% had central adiposity, 11.4% showed low HDL cholesterol, and 17.9% exhibited elevated blood pressure. Individuals with an elevated TG/HDL-c ratio demonstrated significantly higher waist circumference, WtHR, METS-VF, triglycerides, non-HDL cholesterol, fasting glucose, blood pressure, and TyG index values (all p < 0.001). A progressive worsening of lipid and metabolic parameters was observed across increasing METS-VF quartiles. Elevated TG/HDL-c ratio prevalence increased from 2.7% in the lowest METS-VF quartile to 15.8% in the highest quartile. Men showed a substantially higher prevalence of residual atherogenic dyslipidemia than women (12.2% vs. 3.9%, p < 0.001). Physical inactivity, smoking, poor Mediterranean diet adherence, and regular alcohol consumption were strongly associated with adverse lipid-metabolic profiles. In multivariable analyses using separate adiposity measures, BMI and METS-VF remained independently associated with elevated TG/HDL-c, whereas WtHR ≥ 0.50 was not independently associated after adjustment. Male sex, physical inactivity, smoking, impaired fasting glucose, elevated blood pressure, and low Mediterranean diet adherence showed consistent associations across models. Conclusions. Residual atherogenic dyslipidemia is highly prevalent among adults with normal BMI and is strongly associated with visceral adiposity, metabolic dysfunction, and unfavorable lifestyle-related behaviors. Conventional BMI classification alone substantially underestimates hidden cardiometabolic risk. These findings highlight the metabolic heterogeneity present among apparently healthy normal-weight individuals and the limitations of BMI as a sole marker of cardiometabolic health.