On the same day, hypothalamic activation pattern(s) will be evaluated in patients and in control subjects by fMRI. After basal evaluation, all the groups will receive a standard oral meal, i.e., a 200 mL hypercaloric oral nutritional supplement providing 300 Kcal, and then a second fMRI scan will be performed. Using a computerized software, the average value of the grey for the hypothalamus will be calculated, and normalized for the one obtained in the basal condition, to obtain the percentage (%) of activation (or inhibition) of the hypothalamus.