Obesity and overweight, as a part of the metabolic syndrome, are well known risk factors for the development of diabetes, hypertension, coronary heart disease, hyperlipidemia, stroke, sleep apnea syndrome, osteoarthritis and certain forms of cancer. Cardiovascular disease remains the leading killer in industrialized countries, where it accounts for 40% of deaths. Obesity is defined either by increased waist circumference, waist to hip ratio, or body mass index. Obesity results from an interaction of genes and lifestyle. As people in both developed and developing countries eat more and more energy dense food, and have ever less physical activity, the number of overweight and obese people increases to epidemic proportions. Abdominal obesity plays a key role in the pathophysiology of metabolic disorders, is associated with insulin resistance, and predicts the development of type 2 diabetes and subsequent coronary artery disease. In the general population, obesity is associated with an increased mortality, but paradoxically, a positive correlation between body mass index and survival in congestive heart failure has been reported. In secondary prevention, obesity is underrecognized, underdiagnosed and undertreated in persons with cardiovascular diseases. Weight loss and prevention of weight gain have to be considered one of the most important strategies to reduce the incidence of cardiovascular disease. Increased physical activity and appropriate diet are the cornestones of treatment. Considering the high prevalence of overweight and obesity in Croatia, there is urgent necessity to improve the level of knowledge and skills in understanding obesity by health care services, and to implement appropriate professional strategy to achieve the desired lifestyle modifications.