In a group of 126 obese subjects hospitalized at the obesitological unit of the Gerontological and Metabolic Clinic, Faculty Hospital Hradec Králové the authors confirmed the effect of short-term modified fasting and a low energy diet on the body weight and body mass index They also proved the influence of weight reduction on normalization of cholesterol and LDL-cholesterol and tria- cylglycerols. They did not prove however the influence of short-term modified fasting and a low energy diet on the concentration of some coagulation pareameters (fibrinogen, D-dimers, antithrombin). In the patients a decline of the fibrinolytic activity was observed and an increase of the fibrinolytic capacity. The authors found a close correlation between the decline of the inhibitor of plasminogen-1 activator, an indicator of the fibrinolytic activity, and body weight and lipid changes. The authors proved a close negative correlation between the rise of fibrnolytic capacity and changes of body weight and lipids. In conjunction with the presented results and based on data from the lierature it may be stated that a decline of body weight in obese subjects reduces the risk of the syndrome of insulin resistance. Activation of fibrinolysis in insulin resistance depends directly on the amount of visceral fat and changes of te fibrinolytic properties of blood in obese subsjects depend on the production of PAI-1 by adipocytes of visceral fat.

        Key words: Obesity - Weight reduction - Fibrinolysis