The influence of caloric restriction and of weight loss during a weight-maintaining diet on lipid profile and in particular on high density lipoprotein (HDL) is controversial. In this study we analyzed the effect of a period of very low caloric diet (VLCD) and of a period of hypocaloric diet followed by 30 days of weight stabilization on lipoprotein levels, especially on HDL cholesterol and its subfractions (HDL2 and HDL3) and on the summated means of glucose (Σ glucose) and insulin levels (Σ IRI) after an oral tolerance test in a group of obese females. Body weight decreased significantly during the VLCD and hypocaloric diet. Total cholesterol decreased significantly after the VLCD and hypocaloric diet, but after the period of the weight-maintaining diet it was superimposable to the initial value. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol behaved like total cholesterol. HDL2, HDL3 and HDL cholesterol decreased significantly after the period of VLCD. Then, after the hypocaloric diet the values of HDL2, HDL3 and HDL cholesterol returned towards the initial values and only after the period of the weight-maintaining diet did their values increase significantly. Σ glucose did not vary significantly at any time of the study, while Σ IRI reduced significantly both after the hypocaloric diet and the weight-maintaining diet. HDL2 and HDL cholesterol changes were found to be positively correlated to the variations of Σ IRI both at day 45 and 75 of the study. The results of our study show that the weight loss is associated with an increase of HDL cholesterol values and that plasma insulin may be one of the determinants of its variation.