Obesity is a civilization disease of the 21st century. It affects a growing percentage of the population. The most common cause of obesity is excessive caloric intake – then we can diagnose simple obesity. It corresponds to over 90% of cases. Secondary obesity is when it is caused by another disease or certain medicines. Some genetic syndromes, endocrine diseases – especially Cushing's syndrome and hypothyroidism, brain trauma – can lead to weight gain. During the patient's examination, attention should be paid to the presence of additional symptoms accompanying obesity, which may suggest another condition underlying obesity. An important group of drugs that play a role in weight gain are psychotropic drugs – especially neuroleptics used in the treatment of schizophrenia. Obesity is not only an aesthetic problem, but can cause serious complications. It can lead to the development of cardiovascular disease, diabetes and even cancer.

Key words: obesity, secondary obesity, hypothyroidism, neuroleptics, genetic diseases.