Today I noticed this very readable open access paper that reviews calorie restriction research and ongoing efforts to produce drugs that can mimic some of the beneficial effects of calorie restriction on health and longevity. It can be downloaded in PDF format from the journal website:
Everyone desires a long and healthy life, and many researchers have investigated methods to overcome and to retard the aging process. The most well defined intervention of retarding aging is caloric restriction. Caloric restriction, also known as dietary restriction, is the reduction of food intake without malnutrition. Experimentally, caloric restriction means a reduction in calorie intake by 10-30% when compared to an ad libitum diet. Lifespan extension in response to caloric restriction is thought to be caused by a decreased rate of increase in age-specific mortality. It is widely believed that caloric restriction delays the onset of age-related decline in many species, as well as the incidence of age-related diseases such as cancer, diabetes, atherosclerosis, cardiovascular disease, and neurodegenerative diseases. Caloric restriction affects the behavior, animal physiology, and metabolic activities such as modulation of hyperglycemia and hyperinsulinemia, as well as increases insulin sensitivity.
Reductions of protein source in the diet without any changes in calorie level have been shown to have similar effects as caloric restriction. Furthermore, restriction of individual amino acids has been shown to induce lifespan extension in some species, especially methionine restriction. Moreover, the restriction of tryptophan is believed to have a positive effect on longevity. Thus, several researchers have stated that this phenomenon occurs as a result of dietary restriction, not caloric restriction. However, other studies have indicated that protein and/or methionine restriction is not involved in the caloric restriction-induced lifespan extension.