This study presented a newly developed online groupware system, Metaboli-Net, to yield counseling guidance on diet and exercise to patients with metabolic syndrome. A distinctive feature adopted in the system to maintain the retention rate of patients was the social network service (SNS) that enables the patients to share their dietary and relevant health information with other participants in the same group on the network. A pilot study was conducted to prove the effectiveness of the system in improving the patient's lifestyle and dietary health awareness. SNS also contributed to the participant's adherence to intervention programs.