Modeling and projecting the obesity prevalence have an important implication in the evaluation of mortality risk. A large volume of literature exists in the area of modeling mortality rates, but very few models have been developed for modeling obesity prevalence. We developed the CBD-O stochastic model for modeling the obesity prevalence that accounts for an age and period effect as well as a cohort effect. The CBD-O model is used to model obesity prevalence for the United States population, aged 23-90, during the period 1988-2012. Forecast is validated in comparison to the actual data for the period 2013-2015.