International consensus on fasting terminology
Daniela A. Koppold, Carolin Breinlinger, Etienne Hanslian, Christian S. Keßler, Holger Cramer, Anika Rajput Khokhar, Courtney M. Peterson, Grant M. Tinsley, Claudio Vernieri, Richard J. Bloomer, Michael Boschmann, Nicola Luigi Bragazzi, Sebastian Brandhorst, Kelsey Gabel, Alan Goldhamer, Martin M. Grajower, Michelle Harvie, Leonie K. Heilbronn, Benjamin D. Horne, Spyridon Ν. Karras, Jost Langhorst, Eva Lischka, Frank Madeo, Sarah J. Mitchell, Ioannis A. Papagiannopoulos, Maria Papagiannopoulou, Hanno Pijl, Éric Ravussin, Martha Ritzmann-Widderich, Krista A Varady, Lilian Adamidou, Mélika Chihaoui, Rafael de Cabo, Mohamed Hassanein, Nader Lessan, Valter D. Longo, Emily N. C. Manoogian, Mark P. Mattson, Joseph B. Muhlestein, Satchidananda Panda, Sousana Κ. Papadopoulou, Nikolaos E. Rodopaios, Rainer Stange, Andreas Michalsen
Abstract
Although fasting is increasingly applied for disease prevention and treatment, consensus on terminology is lacking. Using Delphi methodology, an international, multidisciplinary panel of researchers and clinicians standardized definitions of various fasting approaches in humans. Five online surveys and a live online conference were conducted with 38 experts, 25 of whom completed all 5 surveys. Consensus was achieved for the following terms: "fasting" (voluntary abstinence from some or all foods or foods and beverages), "modified fasting" (restriction of energy intake to max. 25% of energy needs), "fluid-only fasting," "alternate-day fasting," "short-term fasting" (lasting 2-3 days), "prolonged fasting" (≥4 consecutive days), and "religious fasting." "Intermittent fasting" (repetitive fasting periods lasting ≤48 h), "time-restricted eating," and "fasting-mimicking diet" were discussed most. This study provides expert recommendations on fasting terminology for future research and clinical applications, facilitating communication and cross-referencing in the field.