The last decades, obesity represents one of the most serious health issues with approximately 310 million people presently affected globaly and is frequently cited as a chronic disease. The term obesity refers to the excessive accumulation of fat, mainly under the skin but also on various organs of the body. Obesity’s most common cause is the intake of more calories than those required for one’s daily needs. The aim of the study was to review etiology of obesity, as well as the accountable risk factors. The method οf this study included bibliography research from both the review and the research literature which referred to the etiology, the risk factors of obesity and the beneficial role of physical exercise on weight management. Results: The majority of research studies showed that a growing number of adults, children and adolescents around the world, is facing the danger of becoming obese. In literature is cited that both genetic and environmental factors are accountable for the development of obesity. It is well established that the main therapeutic approaches to loose weight are life-style modifications and the combination of a well-balanced hypocaloric diet with regular physical exercise. Conclusions: The problem of obesity and overweight has become an epidemic in most developed countries. The rapid increase in the numbers of obese people reflects environmental changes, the reduced activity and also the increased food intake.