This study aimed to test a conceptual model of associations between socio-demographic and behavioral factors and obesity in the Tehran Lipid and Glucose Study (TLGS). Data from 2747 TLGS adult participants (58.3% female) were analyzed. Socio-demographic and behavioral factors in the conceptual model were tested for their direct and indirect associations with overweight and central obesity, using structural equation modeling (SEM), conducted by IBM SPSS AMOS software. Overweight and central obesity were found in 61.6 and 48.1% of respondents, respectively. Fit indices were acceptable for the conceptual model. Daily energy intake had a direct association with overweight and central obesity in both genders; however, poor dietary pattern had direct associations with overweight and central obesity only in men. In women, age, marital status, and level of education had direct associations with overweight and central obesity. In men, only age and marital status had direct associations with overweight and central obesity. Age and marital status in both genders and level of education only in women were among the socio-demographic factors which were directly associated with both overweight and central obesity. Among behavioral factors, daily energy intake was the most important factor that was directly associated with both overweight and central obesity in both genders. Adherence to poor diet directly was associated with overweight and central obesity only in men. The current findings provide beneficial information for designing culturally relevant and effective interventions/strategies for prevention of overweight among Tehranian adults.