Intermittent feeding schedules : behavioural consequences and potential clinical significance

Peer reviewedPublisher PD

New elements in modern biological theories of aging

Generally and simply speaking, when human individuals think of how their bodies are aging, probably the most visible changes come first to their minds. One can notice more grey hair or the skin does not seem as smooth as it used to be. These are just external signs of a series of processes going on within our cells and bodily systems that together constitute normal aging. Aging (also called senescence) is an age-dependent decline in physiological function, demographically manifesting as decreased survival and fecundity with increasing age. Aging is also commonly defined as the accumulation of diverse deleterious changes occurring in cells and tissues with advancing age that are responsible for the increased risk of disease and death. The principal theories of aging are all specific of a distinct cause of aging, giving useful and deep insights for the understanding of age-related physiological changes

Energy tradeoffs between food assimilation, growth, metabolism and maintenance

The effect of metabolic rate (MR) on organisms\u27 health maintenance is a long-standing puzzle and empirical data on this issue is contradictory. A theoretical model was developed for understanding animal\u27s energy budget under the food condition of Ad libitum (AL) and food restriction. This model offers a framework for understanding the role of MR and health maintenance mechanism from the perspective of energy tradeoff between food assimilation, growth, metabolism and maintenance. Hornworm (Manduca sexta larva) has been selected as an model to test the energetic tradeoff under different food supply and ambient temperatures. The changes in energy budget can reveal its health maintenance mechanism during growth. The experiments\u27 results show that (1) under food restriction, high temperature can slow down the growth rate to compensate for the high metabolism; (2) the free-feeding larvae slightly decrease the energy allocated to growth as body mass increases, and increase the energy allocated to metabolism, while the food restricted larvae prioritize growth at the expense of metabolism; (3) during growth, the mainly reason of the accumulated damages is caused by the changes in biosynthesis instead of the changes in metabolic energy --Abstract, page iv

The aging process and potential interventions to extend life expectancy

Aging is commonly defined as the accumulation of diverse deleterious changes occurring in cells and tissues with advancing age that are responsible for the increased risk of disease and death. The major theories of aging are all specific of a particular cause of aging, providing useful and important insights for the understanding of age-related physiological changes. However, a global view of them is needed when debating of a process which is still obscure in some of its aspects. In this context, the search for a single cause of aging has recently been replaced by the view of aging as an extremely complex, multifactorial process. Therefore, the different theories of aging should not be considered as mutually exclusive, but complementary of others in the explanation of some or all the features of the normal aging process. To date, no convincing evidence showing the administration of existing “anti-aging” remedies can slow aging or increase longevity in humans is available. Nevertheless, several studies on animal models have shown that aging rates and life expectancy can be modified. The present review provides an overlook of the most commonly accepted theories of aging, providing current evidence of those interventions aimed at modifying the aging process