Blood platelets play a central role in the physiology of primary haemostasis and in the pathophysiological processes of arterial thrombosis. Since the platelet volume reflects platelet activity, the mean platelet volume (MPV) is a further independent risk factor for cardiovascular disease. Although it is well established that weight reduction reduces some risk factors of cardiovascular disease in obese patients, an increase of MPV occurs during the period of weight loss. In two groups of 46 obese patients (the first group of 24 patients with short-term modified fasting, the second of 22 patients with a very low calorie diet) the authors confirmed the effect of modified fasting and a low calorie diet on the body weight and body mass index. They also proved in both groups a major decrease of cholesterol values (p<0.01 vs p<0.05) and triacylglycerols (both p<0.01) and observed an increase of MPV (p<0.05) during weight reduction.These results indicate that patientswith preexisting atherosclerosis and an increased MPV during weight reduction procedures are at high risk of contingent thromboembolic ischaemic events.MPV represents a simple routine haematological parameter, but a possible benefit from preventive treatment in patients with cardiovascular disease is unknown.

        Key words: mean platelet volume (MPV), body weight reduction,modified fasting, very low calorie diet