Aging is associated with a wide variety of physiological changes that compromise the ability of the body to respond to stress or change, and ultimately contribute to morbidity and mortality.  Much research has been done on the aging process in humans and experimental animals, and the impact of diet, but there is relatively little data from companion animal studies.  However, although many of the aging changes are likely to be similar between different mammals, it is known that there are some differences with cats. 

In contrast to dogs and humans, elderly cats experience an increase in their maintenance energy requirements rather than a continued decline, which may be mediated partly through a better-maintained basal metabolic rate but also through progressive compromise in fat and protein digestion.  Old age is also associated with a progressive loss of lean body mass that may be mitigated in part by feeding higher protein levels.  Diets designed for healthy elderly cats should therefore concentrate on being energy dense, highly digestible and with an increase in the proportion of protein calories, and being fed with the aim of supporting optimal body weight.  There is also strong evidence emerging that dietary manipulation in cats may be able to modify aspects of the aging process, with a long-term longitudinal study of cats demonstrating both survival and health benefits from feeding a diet supplemented with antioxidants, fatty acids, and a prebiotic source.