Recently, the World Health Organization classified obesity as an epidemic disease of the modern era. More and more scientific reports draw attention to a correlation between obesity and the physio‑chemical and biochemical changes occurring in the saliva. Studies continue to show that adults and adolescents utilise different types of diets to lose or maintain weight. Nevertheless, the prevalence of overweight and obesity has been increasing continuously over the last 30 years. The basis for the treatment of obesity is to achieve a negative energy balance, which is possible through the implementation of an energy‑reduced diet in relation to a patient's needs and increased physical activity. One of the methods used in the treatment of obesity is the use of a very low calorie diet (VLCD), which provides 200–800 kcal per day. A VLCD diet is considered to be a diet that reduces body weight, which in turn is associated with a reduction in hypertension, dyslipidemia and diabetes.

Key words: saliva, obesity, oral health, very low calorie diet (VLCD).