Neck Circumference as a Surrogate Marker of Upper-Body Adiposity: Associations with Anthropometric, Biochemical and Inflammatory Cytokines in Mexican Adults with Obesity

Background: Neck circumference (NC) is a simple anthropometric index of upper-body subcutaneous adiposity. Its relationship with inflammatory cytokines, particularly the anti-inflammatory cytokine IL-10, remains poorly explored, especially in Latin-American populations. Methods: This cross-sectional study analyzed data from 80 Mexican adults with obesity (40 women and 40 men). NC, waist circumference (WC), and body mass index (BMI) were measured according to standardized ISAK and NHANES protocols. Fasting glucose, insulin, lipid profile, and HbA1c were evaluated. Finally, serum TNF-α, IL-6, IL-18, IL-10, and hs-CRP were quantified from a subsample. Correlation coefficients and sex-stratified multiple linear regression models adjusted for age and BMI were performed. Results: In the overall sample, neck circumference (NC) was positively associated with triglycerides, VLDL-C, insulin, and HbA1c, and inversely associated with HDL-C. Sex-stratified analyses revealed marked differences. In women, NC showed strong and independent associations with triglycerides, VLDL-C, IL-10, and the IL-10/TNF-α ratio, whereas these associations were not observed in men. Similarly, waist circumference was independently associated with IL-10, and BMI was associated with hs-CRP. Conclusions: NC may serve as a useful surrogate marker of upper-body adiposity and is independently associated with triglycerides, VLDL-C, IL-10, and the IL-10/TNF-α ratio exclusively in women with obesity. These exploratory findings highlight sex-specific differences in the adiposity–inflammation axis and underscore the need for larger longitudinal studies and sex-tailored approaches in obesity research.