June 28, 2017
JAMA. Published online June 28, 2017. doi:10.1001/jama.2017.6648
Adecade ago, researchers investigating the antiaging effects of caloric restriction in humans set an ambitious goal for their study participants: decrease daily calories by 25%. On average, the group of nonobese adults were only able to cut down by 12% over the 2-year investigation, despite receiving intensive dietary and behavioral counseling. Significant changes in the study’s primary end points—resting metabolic rate and core body temperature—didn’t materialize either. These 2 factors are believed to slow aging in animal models of caloric restriction. Does that mean the study failed? Not necessarily.
Even though the results weren’t comparable with those in animal models, a few bright spots emerged. The second phase of the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE 2) trial, which was funded by the National Institute on Aging (NIA) and the National Institute of Diabetes and Digestive and Kidney Diseases, demonstrated that it’s feasible for humans to limit calories for an extended period. In addition, participants who cut back on calories lost weight and kept it off for the duration of the study. There were no adverse effects on quality of life and the participants netted improvements in blood pressure, cholesterol, and insulin resistance—all risk factors of age-related diseases.