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United States Department of Agriculture

Agricultural Research Service

Research Project: ENERGY REGULATION DURING THE ADULT LIFESPAN Title: The CALERIE Study: design and methods of an innovative 25% caloric restriction intervention

Authors
item Rickman, Amy -
item Williamson, Donald -
item Martin, Corby -
item Gilhooly, Cheryl -
item Stein, Richard -
item Bales, Connie -
item Roberts, Susan -
item Das, Sai Krupa -

Submitted to: Contemporary Clinical Trials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2011
Publication Date: July 8, 2011
Citation: Rickman, A.D., Williamson, D.A., Martin, C.K., Gilhooly, C.H., Stein, R.I., Bales, C.W., Roberts, S.B., Das, S. 2011. The CALERIE Study: design and methods of an innovative 25% caloric restriction intervention. Contemporary Clinical Trials. 32(6):874-881.

Interpretive Summary: Animal studies have shown that life span is extended by caloric restriction (CR). The purpose of the Comprehensive Assessment of the Long-term Effects of Reducing Energy Intake (CALERIE) Study is to examine the effects of long-term 25% CR on non-obese humans. The study was undertaken to examine 2 years of sustained CR on: a) slowing the aging process as assessed by proxy indicators and b) protecting against age-related disease processes. The distinct difference between CALERIE and previous weight loss studies is that CALERIE emphasizes adherence to a prescribed CR goal rather than to a specified degree of weight loss. To tackle the challenge of assisting participants in achieving and maintaining the 25% CR goal for 24 months, an intensive intervention was designed. This manuscript provides an overview of the innovative study design and methods used in a CR intensive intervention, and may be of assistance for other researchers and clinicians in designing and implementing future trials.

Technical Abstract: Animal studies have shown that life span is extended by caloric restriction (CR). This manuscript describes the design and methodology of an innovative CR intervention, which is the treatment arm of the CALERIE Study. This study is a multi-center, randomized, controlled trial examining the effects of 2 years of CR on biomarkers of longevity among non-obese (BMI=22 kg/m2 and b28 kg/m2) adults. CALERIE is the first investigation of the effects of long-term CR on the aging process in non-obese humans. Two-hundred twenty healthy volunteers across 3 sites were recruited beginning in May 2007. Participants were randomized in a 2:1 ratio between the CR or control group (i.e., ad libitum diet). An intensive intervention was designed to assist participants in adhering to the 25% CR prescription for a 2-year duration. The intervention was designed to optimize the likelihood that 25% CR would be achieved through a variety of nutritional and behavioral strategies, several of which are innovative methods for achieving CR. The intervention includes the following components: an intensive, “mixed” format schedule of group/individual sessions, meal provision phase with exposure to various diets, Personal Digital Assistants to monitor caloric intake, unique portion estimation training, tailored treatment using a computer tracking system, toolbox strategies and algorithms, as well as comprehensive coverage of nutrition and behavioral topics in order to assist participants in meeting their CR goal. This manuscript provides an overview of the CR intensive intervention and may be of assistance for other researchers and clinicians in designing future trials.

Last Modified: 10/21/2014
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