Multivariable Associations of Anthropometric and Psychosocial Markers with an Elevated Abdominal Volume Index Among University Students: A Sex- and Academic Program-Stratified Analysis

Background: The Adiposity Volume Index (AVI) is a modern geometric tool for tracking central body fat. However, how it interacts with prenatal markers (2D:4D ratio), advanced anthropometric indexes, and psychological factors across different academic disciplines remains largely unexplored. This study evaluates the sex-specific association profiles and screening capacity of these parameters in healthy university students. Methods: A cross-sectional study was conducted on 445 students (199 men and 246 women) from Biomedical Sciences (BS), Computer Science and Engineering (CSE), and Social Sciences and Physiotherapy (SSP) academic programs. Anthropometric indicators (Body Mass Index—BMI, Body Surface Area—BSA, Weight-adjusted Waist Index—WWI, Sagittal Abdominal Diameter-to-Waist circumference Ratio—SAD-to-Waist Ratio), the right-hand digital 2D:4D ratio (R-2D:4D), and Perceived Stress Questionnaire scores (PSQ) were assessed. Data were analyzed using multi-layered linear regression and ROC curve analysis. Results: In male students, BMI, BSA and WWI consistently co-varied with AVI across all academic programs (R2 > 0.978, p < 0.001). In contrast, a major psychosomatic interaction emerged in female students. Among stressed BS students, the linear association model shifted (R2 = 0.313, lost significance), and the prenatal R-2D:4D ratio became a significant negative independent correlate (B = −87.780, p = 0.019). ROC analysis revealed that optimal BMI cut-offs for elevated AVI were 26.96 kg/m2 (AUC = 0.957) for men and 24.89 kg/m2 (AUC = 0.972) for women. Notably, perceived stress was a significant diagnostic marker only for female students (AUC = 0.621, p < 0.001, cut-off = 65.50). Conclusions: Perceived academic stress exhibits a significant concurrent association with abdominal fat distribution patterns exclusively in female biomedical students, co-varying with prenatal endocrine markers within the studied cohort. Furthermore, AVI-driven screening demonstrates that metabolic vulnerabilities in these young adults may accumulate within the conventional normal-weight BMI range for women, emphasizing the potential utility of sex-tailored clinical assessments.