Each child will arrive at the UOC at 8 a.m., in fasting. A blood sample will be taken. Then patients will be given two LibramedR tablets or placebo. After 20 minutes they will be given a mixed meal (equal to 15 kcal per kg of lean body mass). Blood samples will then be taken at 30-minute intervals for the first two hours and 60 minutes for the following two hours, for the determination of metabolites and hormones for a total of 4 hours. The level of satiety will be quantified through a visual analog scale.