Atypical antipsychotic treatment is associated with weight gain and increased metabolic risk. This systematic literature review evaluates the current research on the effectiveness of behavioural interventions in treating and preventing atypical antipsychotic weight gain and reducing metabolic risk, describes characteristics of interventions implemented and discusses findings in the context of the RE-AIM framework. Sixteen studies were identified. When initiated at the start of treatment with an atypical antipsychotic agent, behavioural weight loss interventions decreased the amount of weight gain associated with atypical antipsychotic treatment. When behavioural interventions were initiated after the start of atypical antipsychotic treatment, these interventions were associated with weight loss. Mean weight losses across studies by treatment duration were 2.63 kg for 12- to 16-week interventions, 4.24 kg for 6-month interventions and 3.05 kg for 12- to 18-month interventions. Behavioural weight loss interventions were also found to improve insulin regulation and HbA1c. In addition to assessing efficacy, future studies should evaluate other components of the RE-AIM framework, including reach, adoption, implementation and maintenance. This information will be useful in determining what types of interventions are both effective and practical for delivery in health care or community mental health settings.