<qa>  What is the main reason for the increase in obesity?The recent dramatic rise in the prevalence of obesity has heightened awareness of the significant impact of overweight, physical inactivity, and unhealthy eating patterns on the development of chronic diseases and disability While there is little doubt that obesity and associated lifestyle factors e.g., sedentary lifestyle constitute serious threats to health, it is also clear that lifestyle interventions can produce body weight reductions of sufficient magnitude to improve health. The existing research is limited, however, with respect to two important factors, specifically, its generalizability to underserved populations, and the maintenance of treatment effects. Most weight-loss trials have consisted of efficacy studies conducted with middle-class participants and delivered in optimal i.e., academic research venues rather than in real world i.e., community settings. Furthermore, the existing literature shows that, in the absence of long-term care, a regaining of lost weight routinely follows the conclusion of treatment. Recent research has shown improved maintenance of lost weight when lifestyle interventions are supplemented with clinic-based follow-up programs. Thus, the next logical steps in this line of research are a to extend these studies to community settings with underserved populations and b to test promising alternative and potentially more efficient modes of treatment delivery, such as follow-up care via telephone-based contacts rather than via in-person clinic visits. 