Background: obesity is highly associated with poor health outcomes including many chronic diseases. Rural Appalachia has higher rate of obesity in the nation. However, obesity can be prevented by consuming small portion size. There is scarcity of public health theories that can predict the likelihood of initiation and sustenance of small portion size consumption behavior. Multi-theory model (MTM), developed recently has shown strong predictability of modifiable health behaviors. _x000D_ Objective: This study examined the association between MTM components changes in social environment, practice for change, and emotional transformation with the sustenance of small portion size consumption behaviors in rural Appalachia. _x000D_ Material and Method: A standardized MTM instrument for modifiable health behavior available in public domain was adapted and used for portion size consumption behavior. A cross-sectional research design and a convenience sampling were applied. Data was collected from six counties which are defined as distressed, at risk, and transitional mainly on the economic indicators by the Appalachian Research Commission (ARC). Direction and strength of the association between likelihood of sustaining small portion size consumption behavior and the components of sustenance model of MTM was assessed. Chi-square statistics was used for assessing the difference in sustenance behavior with sociodemographic factors including gender, education, employment, and ethnicity._x000D_ Results: A total of 156 people 92 (59%) males and 63(40.4%) females, age range 18 to 91 (39.22 + 19.02) years old who consumed large portion sizes in past 24 hours were included in the analysis. Majority of the participants were White (85.3%). More than half had high school education (51.9%) and were employed (61.5%). Spearman’s correlation has found a positive correlation between the MTM components emotional transformation (rs = 0.56), practice for change (rs = 0.55), and changes in social environment (rs = 0.35) with the likelihood of small portion size consumption behavior (p
