Scientists reach consensus for fasting terminology

Dr. Eric Ravussin of Pennington Biomedical Research Center in Baton Rouge was one of 38 scientists from five continents to present the first international consensus on fasting terminology and key definitions. Published in Cell Metabolism, the recent study reflects the increasing popularity of diets tied to fasting and a significant increase in scientific studies of fasting. While the application of fasting is rapidly growing, there was previously no globally established terminology.

The panel was the first to bring together experimental and clinical experts in medical and religious fasting. Twenty-four terms were defined as panelists collaborated across a live conference and five online surveys. Some of the major terms defined include “fasting,” “modified fasting,” fluid-only fasting,” “alternate-day fasting,” “prolonged fasting,” and “religious fasting,” among others.

“Despite the fact that fasting is being studied extensively around the world, especially in relationship to healthy aging, there was no common definitions of the different approaches to fasting and caloric restriction,” said Dr. Ravussin, who is a professor of diabetes and metabolism at Pennington Biomedical. “By defining these terms and setting a standard, we can help steer people away from those unverified diets that mislead participants into unhealthy or even dangerous behaviors. The application of fasting has proven to be beneficial and popular, and as its use grows, we wanted to ensure researchers, dieticians, nutritionists, and fitness instructors are aligned with clear, universal terminology.”

Using the Delphi method—a communication technique to generate a consensus through a series of questionnaires—the multidisciplinary panel of researchers reached consensus on these terms to better facilitate communication and cross-referencing in the field.

Scientists from around the world who were approached to participate in the panel primarily specialized in dietary approaches to increasing both health and potentially lifespan, as well as impacting the known biomarkers of aging. Dr. Ravussin is a well-known researcher in this field, and his work on the panel began in 2002.

“Dr. Ravussin’s contributions to this panel are not only important for the consensus that was reached, but for furthering Pennington Biomedical’s reputation as a leading global voice in these industry-wide guidelines that will provide clarity and consistency to researchers around the world,” said Pennington Biomedical Executive Director Dr. John Kirwan. “His contribution on the plan furthers our leadership role contributing to the knowledge base and improving health across the lifespan.”

Some of the better-known words whose definitions were formally agreed upon through the survey include:

• Fasting—voluntary abstinence from some or all foods or foods and beverages.
• Modified fasting—restriction of energy intake to a maximum of 25% of energy needs.
• Fluid-only fasting—a modified fasting regimen whereby only beverages are consumed for a certain period of time.
• Alternate-day fasting—alternating a day of eating ad libitum and a day of water-only fasting.
• Short-term fasting—fasting that lasts two to three days.
• Prolonged fasting—fasting for greater than or equal to four consecutive days.
• Religious fasting—any fasting regime that is undertaken as part of a religious practice.
• Intermittent fasting—repetitive fasting periods lasting equal to or less than 48 hours.