In this project, investigators plan to conduct a randomized control trial of a weight loss intervention that is remotely delivered via SNS among the obese adult patients (20-64 years old, BMI ≥ 27 kg/m2) recruited from weight control clinic in a tertiary medical center in Taipei. Investigators will survey the participants' baseline characteristics at different dimensions including personal, behavioral, physiological, socio-environmental factors. Participants will be randomly assigned to a 16-week weight loss program of either enhanced intervention via Facebook group or standard intervention. After the intervention, the participants will be followed until 2 years after enrollment. Investigators will measure participants' change in weight as well as change in attitude, behavior, and physiological along the follow-up periods. Investigators proposed specific study aims as following: (1) Demonstrate the characteristics of the obese patient who visiting weight-control clinics at behavioral level, physiological level, and social level. (2) Implement an enhanced weight loss intervention by using SNS with personalized feedback (3) Investigate the social influence and the interaction between participants in the social networking site (4) Test the hypothesis that, compared with a standard behavioral weight loss intervention, the enhanced intervention would result in greater weight loss and physical benefit (5) Test the hypothesis that, the enhanced intervention would result in improvement on heath attitude, literacy, or behavior and minimize the attrition of weight loss program (6) Explore the trajectory of individual characteristics throughout the treatment course (7) Explore the predictor or correlate of successful weight loss, maintenance and attrition (8) Investigate the interrelationship between different behavioral, physiological, and environmental factors and their composite effect on weight loss (9) Refine the intervention and develop a further effective and individualized behavior intervention for weight loss

Obesity with its increasing prevalence has become a global health problem. Even modest weight loss induced by lifestyle intervention can produce clinically meaningful health benefits, however, most participants in the weight loss program fail in the longer term because of poor adherence and easy weight regain. An effective behavior therapy for weight loss is believed to have two core elements: (1) a convenient program focusing on individual response and variability, and (2) a better understanding of the predictors and correlates of weight loss outcome. Nowadays, the internet-based program featured with dynamic materials and personalized feedback has been utilized as a novel tool for weight loss. Besides, social networking site (SNS), such as Facebook, is a web-based platform for interaction. Increasing evidence demonstrated interventions through SNSs had substantial potentials on social influence and health behavior change. Research about the effectiveness of weight loss intervention via SNSs has gained much concern in recent years. Predictions of weight loss outcome based on personal characteristics are under investigation for several decades. Identifying predictors or correlates to weight loss outcome can help optimize the efficacy of the program through a better matching of intervention. Because weight loss is a is a dynamic and complex process encompassing interaction of behavioral, physiological and socio-environmental factors, a multi-factorial approach is required for research design. n this 3-year study project, investigators plan to conduct a pilot randomized control trial of a 2-year weight loss intervention that is remotely delivered via social networking site among the obese adult participants (20-64 years old, BMI ≥ 27 kg/m2) recruited from weight control clinic in medical center in Taipei, Taiwan. Investigators will survey the participants' baseline characteristics at different dimensions including personal, behavioral, physiological, social and environmental factors. Participants will be randomly assigned to a 16-week weight loss program of either enhanced intervention via Facebook or standard intervention. After the intervention, the participants will be followed for another 1 year and 8 months. The change in weight will be measured at 6 months, 12 months and 24 months after enrollment. Participants' change in attitude, behavior, and physiological condition will also be measured along the follow-up so that investigators can demonstrate the trajectory and interaction of different variables along the weight loss process. With this 3-year project, investigators not only assess the efficacy of this pilot weight loss program in Taiwan, but investigators also explore the possible predictors and correlates of successful weight loss.

Inclusion criteria:

• Aged 20-64 years
• Body mass index (BMI) ≥27 kg/m2
• Used Facebook or were willing to begin, owned a personal computer or owned a smartphone, and are healthy enough and willing to attend this program with measurement visits in 2 years.

Exclusion criteria:

• Pregnancy
• Previous diagnosis of diabetes mellitus
• History of psychosis, severe anxiety, major depression, panic, or Clinically diagnosed eating disorder
• History of surgical treatment for obesity
• Alcoholism or drug abuse.