It is now well accepted that older persons experience a physiologic anorexia, the anorexia of aging, which is caused by alterations in hedonic qualities of food, fundal compliance, and increased leptin levels. Depression is the most common pathologic cause of weight loss in older persons. Older persons fail to recognize thirst and as such have an increased risk of dehydration. Alterations in brain membrane fatty acids can lead to cognitive impairment in older persons.