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Summary of Findings

Effects of the CALERIE intervention on its primary and secondary outcomes, as well as several exploratory outcomes, are published in A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity. Additional CALERIE 2 publications are available via the search tool in Publications section of this website. The following provides a brief summary of key findings. 

In CALERIE Phase 2, participants achieved 12% CR and sustained 10% weight loss over two years.  In regards to CALERIE’s two primary outcomes, the intervention did not significantly affect core temperature and lowered RMR (adjusted for changes in body energy stores) only in the first year of the intervention. The intervention significantly affected both of the CALERIE secondary outcomes, producing diminutions in circulating levels of both T3 and TNF-ɑ.  It also markedly lowered a variety of cardiometabolic risk factors. 

Caloric restriction at levels achieved in CALERIE was safe and generally well tolerated (with the inherent limitations on conclusions from a trial of limited size). The CALERIE intervention produced a small diminution in bone mineral density, though not in excess of expected changes based on weight. CR at levels achieved in CALERIE Phase 2 had some positive effects and no negative effects on quality of life and psychological outcomes.

As described here, the CALERIE intervention did not significantly affect changes in circulating levels of platelet-derived growth factor AB, transforming growth factor beta, or insulin-like growth factor 1 (IGF-1), which has been proposed to mediate a variety of aging processes, but significantly increased circulating levels of IGF-1 binding protein. It produced small transient elevation on circulating cortisol. 

Other analyses of CALERIE findings are in progress.