Obesity, as an important risk factor for the development of diabetes, cancer or cardiovascular diseases, is one of the most important problems of modern medicine. Studies show that obesity often coexists with psychiatric disorders, including the bipolar disorder (BD) – the prevalence of obesity can be 1.5 times higher in BD patients when compared with the general population. Additionally, the risk of mood disorders in obese patients is also increased. The probable aetiology of the bidirectional relation between BD and overweight and obesity is likely complex – genetic factors, abnormalities in the immune system or an increased frequency of eating disorders are all present. Obesity in BD patients may be associated with an impairment of the mental and physical well-being, poorer co-operation in the treatment and lower quality of life. Drugs used in BD therapy have different predilections for inducing significant weight gain. The highest metabolic risk is associated with olanzapine and clozapine (among antipsychotics), amitriptyline, mirtazapine and paroxetine in the antidepressant group, and among the mood stabilizers (excluding antipsychotics) lithium and valproate. Amongst the possible therapeutic measures in patients with overweight or obesity, nonpharmacological as well as pharmacological procedures are mentioned. The newly registered antipsychotics with a possibly favourable metabolic profile (lurasidon, Cariprazine, and brexpiprazole) as well as the combination of bupropion/naltrexone or bariatric surgery carry interesting prospects for the future.