An international consensus process on fasting terminology was conducted, involving 38 experts from five continents. The process included five online surveys and a live conference, resulting in definitions for 24 fasting-related terms. Key terms defined include "fasting" (voluntary abstinence from food or beverages), "modified fasting" (energy intake limited to 25% of energy needs), "fluid-only fasting," "alternate-day fasting," "short-term fasting" (2–3 days), "prolonged fasting" (≥4 consecutive days), and "religious fasting." Terms like "intermittent fasting," "time-restricted eating," and "fasting-mimicking diet" were discussed extensively. The study provides expert recommendations for future research and clinical applications, promoting clarity and consistency in fasting terminology. The consensus process used the Delphi method, involving expert participation, anonymity, iterative feedback, and statistical aggregation. The final definitions aim to standardize fasting terminology, facilitate communication, and support research and clinical applications. The process highlighted the need for clear definitions to avoid confusion in clinical and research settings. The definitions were agreed upon after multiple rounds of surveys and discussions, with some terms requiring further clarification. The study emphasizes the importance of standardized terminology in fasting research and practice, ensuring consistency and comparability across different studies and clinical applications.An international consensus process on fasting terminology was conducted, involving 38 experts from five continents. The process included five online surveys and a live conference, resulting in definitions for 24 fasting-related terms. Key terms defined include "fasting" (voluntary abstinence from food or beverages), "modified fasting" (energy intake limited to 25% of energy needs), "fluid-only fasting," "alternate-day fasting," "short-term fasting" (2–3 days), "prolonged fasting" (≥4 consecutive days), and "religious fasting." Terms like "intermittent fasting," "time-restricted eating," and "fasting-mimicking diet" were discussed extensively. The study provides expert recommendations for future research and clinical applications, promoting clarity and consistency in fasting terminology. The consensus process used the Delphi method, involving expert participation, anonymity, iterative feedback, and statistical aggregation. The final definitions aim to standardize fasting terminology, facilitate communication, and support research and clinical applications. The process highlighted the need for clear definitions to avoid confusion in clinical and research settings. The definitions were agreed upon after multiple rounds of surveys and discussions, with some terms requiring further clarification. The study emphasizes the importance of standardized terminology in fasting research and practice, ensuring consistency and comparability across different studies and clinical applications.