Obesity is one of the world's leading public health problems. The causes of obesity are many, and the main ones are considered to be a stressful and fast-paced lifestyle, high availability of fast food, unhealthy eating habits and lack of physical activity. The accumulation of adipose tissue, no matter at what age, is closely related to many diseases. That is why it is very important to take care of diet, physical activity and other types of therapy (if necessary). Creating quality prevention programs is an extremely big challenge for public health because it is not easy to raise the awareness of the entire population that obesity is not a harmless disease at all. The aim of this paper is to theoretically present the concept, factors of occurrence and obesity-related diseases, but also to present obesity through all developmental stages. While it is impossible to know what will happen in the future, it is certain that the problem of obesity will not be so easily eradicated. Namely, there will certainly always be people who will still not worry about their health and appearance, the only question is how many such people there will be.