Metabolic disturbances commonly occur with serious mental illness (SMI). Strategies for weight management include group education, peer support, and follow up. This study evaluated the effects of group peer support on body weight, Confidence and Conviction (C&C), diet quality and health-related quality of life in a mental health setting. Fourteen participants [aged 51.7 + /- 12.2 years; four male ten female] who were unable to achieve and maintain 5% weight loss were recruited from a metabolic clinic at a mental health care facility. Weight, C&C, Dietary Screener Questionnaire (DSQ), and 36-item Short Form Survey Instrument (SF-36) were collected at baseline, 3, 6, and 12 months. SF-36 showed significant improvement in Vitality/Energy (-3.823, p = 0.003) and General Health Perception (-2.919, p = 0.014) at 3 months, significant decrease in Physical Functioning (-2.391, p = 0.048) and significant improvement in Pain (-2.885, p = 0.023) from baseline to 12 months. DSQ showed an inverse association between C&C and sugar intake.