Be aware of the links between mental illness and obesity, and ensure you manage the weight gain side-effects of medications used in the treatment of mental illness. Be aware that mental illness can impact obesity manage­ment efforts, and screen patients for potential mental ill­nesses that need to be addressed. Off-indication use of antipsychotics should be avoided, as significant metabolic adverse effects can occur even when these medications are prescribed at lower doses. For patients with severe mental illness who gain weight on antipsychotic treatments, glucagon-like-1-peptides (GLP-1) have the most safety and efficacy evidence among medica­tions indicated for chronic obesity management in Canada. Cost may be a barrier for individuals trying to access this class of medications. When initiating antipsychotic treatment for the first time, avoid medications with higher metabolic risk, as individuals in their first episode respond well regardless of which medi­cation is prescribed (and are at greatest risk for weight gain). Consider switching strategies to a lower metabolic liability antipsychotic in individuals with severe mental illness who gain weight on an antipsychotic treatment. For patients with severe mental illness who gain weight on antipsychotic treatments, metformin can be used in con­junction with behavioural obesity management interventions. Behavioural obesity management therapy, ideally as part of a multi-modal treatment approach, can be effective in managing weight in individuals with co-occurring mental illness. The intensity of the behavioural intervention will need to increase for individuals with more severe psycho­pathology in the context of obesity. Individuals undergoing bariatric surgery should undergo a pre-surgical mental health screen by a qualified bariatric clinician with experience in mental health to identify early risk factors for poor weight-loss outcomes or mental health deterioration. Following pre-surgical screening, individuals should receive ongoing monitoring by a healthcare provider for psychiat­ric symptoms, eating psychopathology and substance use disorders, and for suicidal ideation or self-harm after bar­iatric surgery. For those individuals continuing psychiatric medications after surgery, monitoring of therapeutic effect is critical to maintaining psychiatric stability. Be aware of the links between mental illness and obesity, and ensure you manage the weight gain side-effects of medications used in the treatment of mental illness. Be aware that mental illness can impact obesity manage­ment efforts, and screen patients for potential mental ill­nesses that need to be addressed. Off-indication use of antipsychotics should be avoided, as significant metabolic adverse effects can occur even when these medications are prescribed at lower doses. For patients with severe mental illness who gain weight on antipsychotic treatments, glucagon-like-1-peptides (GLP-1) have the most safety and efficacy evidence among medica­tions indicated for chronic obesity management in Canada. Cost may be a barrier for individuals trying to access this class of medications. When initiating antipsychotic treatment for the first time, avoid medications with higher metabolic risk, as individuals in their first episode respond well regardless of which medi­cation is prescribed (and are at greatest risk for weight gain). Consider switching strategies to a lower metabolic liability antipsychotic in individuals with severe mental illness who gain weight on an antipsychotic treatment. For patients with severe mental illness who gain weight on antipsychotic treatments, metformin can be used in con­junction with behavioural obesity management interventions. Behavioural obesity management therapy, ideally as part of a multi-modal treatment approach, can be effective in managing weight in individuals with co-occurring mental illness. The intensity of the behavioural intervention will need to increase for individuals with more severe psycho­pathology in the context of obesity. Individuals undergoing bariatric surgery should undergo a pre-surgical mental health screen by a qualified bariatric clinician with experience in mental health to identify early risk factors for poor weight-loss outcomes or mental health deterioration. Following pre-surgical screening, individuals should receive ongoing monitoring by a healthcare provider for psychiat­ric symptoms, eating psychopathology and substance use disorders, and for suicidal ideation or self-harm after bar­iatric surgery. For those individuals continuing psychiatric medications after surgery, monitoring of therapeutic effect is critical to maintaining psychiatric stability. For individuals regaining weight after bariatric surgery, psy­chosocial interventions should be used to address comor­bid psychiatric symptoms interfering with obesity manage­ment, such as depression and eating psychopathology, and to support behavioural change long-term. For individuals with binge eating disorder and obesity or overweight, lisdexamfetamine is indicated to reduce eat­ing pathology. Off-label use of topiramate has also been shown to help. Given the prevalence of mental health issues in individu­als with obesity, screening for mental illness (with a focus on depression, binge eating disorder and attention deficit hyperactivity disorder) is appropriate in all patients seeking obesity treatment. Patients with obesity and a mental health diagnosis should be assessed for comorbidities. Physicians should be aware of the weight gain and car­diometabolic risks associated with off-label antipsychotic use (absence of approval by regulatory bodies). The current approved obesity medications can be helpful in patients with a mental illness and should be used based on clinical appropriateness. In people living with overweight or obesity with Binge Eating Disorder, the following medications are effective to reduce eating pathology and weight: lisdexamfetamine, topiramate, and second-generation antidepressants SSRIs duloxetine and bupropion. These medications are effective in reducing eating pathology, but their effect on weight loss is less certain. Patients with comorbid mental illness should be sup­ported with behavioural therapy, preferably as part of a multi-modal intervention, to manage weight. Referral for more intense (i.e., long-term) and behavioural interventions, such as cognitive behavioural therapy, should be considered for individuals with significant binge eating and depressive symptoms in the context of obesity. Patients seeking bariatric surgery should be screened for mental health comorbidities. The presence of an active psy­chiatric disorder does not exclude patients from bariatric surgery but warrants further assessment of potential im­pact on long-term weight loss. Patients should be monitored for alcohol and substance use changes, as well as self-harm/suicidal ideation, after bariatric surgery. They should be informed about altered alcohol me­tabolism following Roux-en-Y gastric bypass surgery. Post-bariatric surgery patients should be monitored for emergence of early postoperative psychiatric symptoms, self-harm and suicidal ideation and eating pathology (given their impact on weight loss outcomes. Patients should undergo pre-bariatric surgery psychosocial assessment by an experienced bariatric clinician. Assessment should continue following surgery and can include the use of either clinician-administered or patient self-report measures. We recommend psychiatric medication monitoring fol­lowing bariatric surgery due to potential changes in drug absorption and therapeutic effect, especially with malab­sorptive surgical procedures. For psychiatric medications with narrow therapeutic index, use of available protocols to manage perioperative levels is warranted. Post-bariatric surgery behavioural and psychological inter­ventions to support maintenance of weight loss and to pre­vent significant weight regain may be useful. Bariatric surgery teams should focus on strategies to im­prove patient engagement during the post-surgery follow-up period, specifically for high-risk patient groups.