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Randomized Controlled Trial
. 2011 Jan;66(1):97-108.
doi: 10.1093/gerona/glq168. Epub 2010 Oct 5.

Design and conduct of the CALERIE study: comprehensive assessment of the long-term effects of reducing intake of energy

James Rochon  1 , Connie W Bales, Eric Ravussin, Leanne M Redman, John O Holloszy, Susan B Racette, Susan B Roberts, Sai Krupa Das, Sergei Romashkan, Katherine M Galan, Evan C Hadley, William E Kraus; CALERIE Study Group
Collaborators, Affiliations
Randomized Controlled Trial

Design and conduct of the CALERIE study: comprehensive assessment of the long-term effects of reducing intake of energy

James Rochon et al. J Gerontol A Biol Sci Med Sci. 2011 Jan.

Abstract

Background: In a robust and consistent manner, sustained caloric restriction (CR) has been shown to retard the aging process in a variety of animal species. Nonhuman primate studies suggest that CR may have similar effects in longer-lived species. The CALERIE (Comprehensive Assessment of the Long-term Effects of Reducing Intake of Energy) research program is the first systematic investigation of CR in nonobese human beings. In the phase 2 study, it is hypothesized that 2 years of sustained CR, involving a 25% reduction of ad libitum energy intake, results in beneficial effects similar to those observed in animal studies. This article presents the design and implementation of this study.

Methods: The study is a multicenter, parallel-group, randomized controlled trial. A sample of 225 participants (22.0 ≤ body mass index [BMI] < 28.0 kg/m(2)) is being enrolled with 2:1 allocation to CR.

Results: An intensive dietary and behavioral intervention was developed to achieve 25% CR and sustain it over the 2 years. Adherence is monitored using a doubly labeled water technique. Primary outcomes are resting metabolic rate and core temperature, and are assessed at baseline and at 6-month intervals. Secondary outcomes address oxyradical formation, cardiovascular risk markers, insulin sensitivity and secretion, immune function, neuroendocrine function, quality of life and cognitive function. Biologic materials are stored in a central repository.

Conclusions: An intricate protocol has been developed to conduct this study. Procedures have been implemented to safeguard the integrity of the data and the conclusions drawn. The results will provide insight into the detrimental changes associated with the human aging process and how CR mitigates these effects.

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Figures

Figure 1.
Figure 1.
Organizational structure for the CALERIE (Comprehensive Assessment of the Long-term Effects of Reducing Intake of Energy) research group. Note: Biochem Lab = biochemistry laboratory; DLW = doubly labeled water; DSMB = data and safety monitoring board; DXA = dual-energy x-ray absorptiometry; NIA = National Institute on Aging; Study Coor = study coordinators; QC = quality control.
See this image and copyright information in PMC

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