In this chapter we have reviewed the evidence for physiological anorexia of 
aging and stressed that its pathophysiology involves both central and peripheral 
mechanisms. Early satiation in the older person appears to involve signals 
predominantly arising in the stomach. The increased feeling of satiety in older 
persons is mainly related to changes in the central feeding drive, in particular 
a decrease in the opioid rewarding properties for fatty foods. Increased 
cytokines, secondary to inflammatory conditions which are common in old age, may 
further increase the anorexia seen in older persons. Leptin, the fat hormone, is 
an excellent indicator of fat mass in women, in whom leptin concentrations 
correlate with the MNA. In men, testosterone inhibits leptin, and the fall in 
testosterone with age results in an increase in leptin concentrations. In males 
the MNA is not related to leptin concentrations. Finally, we have examined the 
interrelation of two nutritional screening indices, MNA and SCALES. The two 
indices were well correlated and were both predictive of poor basic function. We 
conclude that the MNA is an excellent predictor of nutritional status. These 
findings suggest that malnutrition is a major predictor of frailty or the 
"failure to thrive" syndrome in older persons. Depression is a major cause of 
poor nutritional status in older persons.