INS and obesity due to melanocortin 4 receptor deficiency: Xylitol is a well-known sugar substitute and many studies have proven its beneficial effect in terms of glucose tolerance, serum insulin concentration, obesity development prevention, protection of renal and hepatic functions etc., though higher intakes and higher dosages of the sugar alcohols cause several gastrointestinal discomforts, including diarrhea [28,29,30,31].