Caloric restriction for longevity: I. Paradigm, protocols and physiological findings in animal research

Abstract

Abstract The initial article in this series reviews basic findings in the field of caloric restriction for longevity (CRL). To eating disorder specialists, the data are disconcerting. The chronic dieting and subnormal weight we endeavour to prevent and treat in humans appear highly beneficial when imposed on animals. In the laboratory, organisms from nematodes to monkeys thrive when forced to undereat, as long as they receive sufficient micronutrients. The most remarkable results are obtained through the most extreme measures: mice, for example, do best if limited to a third of expected caloric intake, beginning soon after weaning and continuing throughout adulthood. Deprivation can be achieved through an ‘anorexic’ protocol of steady underconsumption or a ‘bulimic’ pattern in which periods of fasting alternate with bouts of binge eating. The benefits of such regimens include delayed senescence, postponement and/or attenuation of age‐related disease and dramatic increases in average and maximum lifespan. Although some biological functions are impaired (including growth, reproduction and perhaps resistance to certain stressors), the cost/benefit ratio clearly favours CRL when calculated on the basis of physical outcomes in late age. Advocacy of comparable regimens for people, however, is ill‐considered. Enthusiasm for CRL can be sustained only by detaching deprivation from the context of daily life, ignoring psychological effects, and dismissing data on human semi‐starvation and eating disorders. The experiences of participants in Biosphere 2 and individuals with anorexia nervosa suggest that the price of CRL is unacceptably high when a wider range of outcome variables is examined. Copyright © 2004 John Wiley & Sons, Ltd and Eating Disorders Association.