Obesity is a major public health concern that increases the risk of cardiovascular disease, type 2 diabetes and cancer. The incidence of obesity has increased significantly in recent years, not only in adults, but also in adolescents and children. This is evidenced by rapidly developing bariatric surgery, the most effective method of treating morbid obesity. Obesity is a multifactorial disease, and its pathogenesis is not completely understood. Numerous studies have been performed to clarify pathogenetic mechanisms, based mostly on blood and sometimes urine samples. Saliva is easily accessible and can be obtained non-invasively. Our aim was to review studies performed on saliva obtained from obese subjects in order to answer the title question.Obese people have different composition of salivary bacteria. Changes in the concentration of sialic acid, phosphorus and peroxidase activity as well as a lower flow rate of stimulated whole saliva promote dental caries and periodontal disease. Concentrations of salivary uric acid, endocannabinoids and CRP are increased in obesity and may provide a useful index of cardiometabolic risk. Assessment of fasting salivary ghrelin might facilitate choosing the best type of bariatric surgery for a specific patient. A significant decrease in salivary cortisol in women with morbid obesity also seems interesting.There is sufficient evidence to state that the saliva of obese and lean subjects is different. Saliva as an easily accessible research material seems promising, as shown by the few studies performed so far.