CCK and Anorexia: Changes in taste and olfactory functions, diminished hunger and altered satiety control mechanism (decreased serum ghrelin and neuropeptide Y (NPY) levels, and increased serum cholecystokinin (CCK), peptide YY (PYY), leptin, and insulin levels), and age-related gastrointestinal motility changes (decreased stomach compliance and delayed gastric emptying) are possible major physiological factors of anorexia of aging [5].