Excessive body weight and obesity have been increasing continuously in recent years, becoming a growing global health problem of modern society. In the USA, obesity is also called the “modern-day plague”, which, in addition to the adult population, increasingly affects the youngest – preschool children. In the 1980s, obesity began to spread massively throughout the world and has reached epidemic proportions today. Due to the disparity between the increased intake of energy through food and the reduced consumption of energy through physical activities, there is an excess of energy that is stored in the body as fat. Obesity is a multifactorial disease most often caused by bad habits related to diet and physical activity. It is worrying that the number of children with increased body weight is increasing and the percentage of obese children is constantly growing. Diagnosing height and weight, and thus potential obesity, is done through regular height measurement and weighing, as well as measuring the body mass index. The result of the body mass index measurement is compared with the recommended reference values. When measuring children, it is important to keep in mind that the recommended values include variables for a certain age and gender due to minor differences in growth between boys and girls. Children with excessive body weight, caused by bad habits, over time develop certain conditions in the body which cause: cardiovascular diseases, metabolic diseases, changes in the locomotor system and body posture. The locomotor disorders are primarily related to the gradual flattening of the feet, the X-shaped and O-shaped leg deformities, as well as various spinal curvature deformities. Education, as a significant component of prevention, primarily consists of informing the parents and raising awareness in them, as they are the models from whom children adopt life habits. A great responsibility lies with pediatricians, kindergarten health managers and kindergarten teachers due to their everyday direct contact with and influence on the child. By carefully selecting foods, spending time outdoors as often as possible and engaging in different activities, the risk of obesity is reduced. Should obesity still occur, this makes it easier to overcome it. Other factors that are closely related to the occurrence of obesity are genetic factors, metabolic factors, the influence of the socio-cultural environment, and natural environment. Treatment of obesity and of the consequences caused by it is challenging, complex, and often long lasting, therefore it is best to prevent its occurrence, or once it has occurred, start with treatment as soon as possible. When obesity is neglected and left untreated, especially if it occurs already in early childhood, the consequences can be seen in the development of various conditions and diseases affecting life quality and expectancy.