At a time when the Internet has become an inseparable part of the everyday lives in the population of developed countries, the awareness of the need for its use in health promotion and disease prevention is continuously increasing. Although there are numerous studies in this field that are still in progress, at the time being we have more open questions than safe answers. Health issues are on the internet dominated largely by unfounded commercial promotions and sales campaigns, while professional content tends to be limited to the official web site of professional societies. Promotion health campaigns that are based on proven and effective -- evidence based platforms are still sporadic. Because of its specificity and longevity, the prevention and treatment of obesity is area of a special interest. It seems that the Internet-based education, practical materials, web -- medical and psychological counseling, and controlled support groups within social networks represent the next major step in the development of effective therapeutic strategies for obesity.