International consensus on fasting terminology

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. [Display omitted] •Thirty-eight panelists from five continents participated in this consensus process•First panel uniting experimental and clinical experts in medical and religious fasts•Twenty-four terms were defined in five online surveys and one live conference•Fasting defined as voluntary abstinence from some or all foods or foods and beverages Although fasting is being studied extensively around the world, there was no common definition of basic terms until now. This publication presents an international consensus process on such terms, including fasting, intermittent fasting, time-restricted eating, long-term and short-term fasting, as well as fasting-mimicking diets.