The widespread observation that caloric restriction will increase longevity must be tempered with the recognition that it has progressively less effect the later in life it is begun,66 as well as with the possibility that the control animals used in these studies feed more than wild animals, predisposing them to an earlier death. Although caloric restriction might extend the longevity of humans, because it does so in many other animal species,67,68,69 there is no study in humans that has proved that it will work. A few people have subjected themselves to a calorically restricted diet, which, in order to be effective, must approach levels that most people would find intolerable. The fact that so few people have attempted caloric restriction since the phenomenon was discovered more than 60 years ago suggests that for most people, quality of life seems to be preferred over quantity of life. The unknown mechanisms involved in the reduced risk of disease associated with caloric restriction are of great interest71 and deserve further study because they could lead to treatments with pharmacological mimetics of caloric restriction that might postpone all age-related diseases simultaneously.
66Weindruch R, Walford RL. Dietary restriction in mice beginning at 1 year of age: effect on life-span and spontaneous cancer incidence. Science. 1992;215(4538):1415-8.
67Weindruch R, Walford RL. The retardation of aging and disease by dietary restriction. Charles C. Thomas. Springfield, IL.; 1988.
68Harrison DE, Archer JR. Natural selection for extended longevity from food restriction. Growth Dev Aging. 1989;53:3-6.
69Duffy PH, Seng JE, Lewis SM, et al. The effects of different levels of dietary restriction on aging and survival in the Sprague-Dawley rat: implications for chronic studies. Aging Clin Exp Res 2001;13:263-272.
70Journal of Gerontology: Biological Sciences. 2001;56,3: entire issue.
71Masoro EJ. Dietary restriction: current status. Aging Clin Exp Res 2001;13:261.
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