Learn Glossary clinical methodology

Intermittent Fasting

Patterns of eating that incorporate regular periods of substantial energy restriction or fasting, including time-restricted eating, alternate-day fasting, and 5:2 schedules.

Also: ADF, Alternate-day fasting, IF, TRE, Time-Restricted Eating, Time-restricted eating

Time-restricted eating limits the daily eating window (often 8-10 hours), aligning with circadian rhythms. Alternate-day fasting and 5:2 alternate fasting and feeding days. Metabolic shifts include depleted glycogen, ketogenesis, and AMPK/SIRT activation. Clinical trials show comparable weight loss to continuous caloric restriction without superior cardiometabolic benefit, with adherence as the main predictor of success.

How each textbook covers it

  • Krause and Mahan's Food and the Nutrition Care Process, 16th ed.Chapter 21

    Common forms: 16:8 time-restricted eating (16 hours fasting, 8 hours eating), 5:2 (5 normal eating days, 2 very-low-calorie days), alternate-day fasting. Short-term studies show similar weight loss to continuous calorie restriction. Long-term adherence and cardiometabolic benefits remain under investigation. Not appropriate during pregnancy, in people with eating disorder history, or with certain medications.

  • Modern Nutrition in Health and Disease, 12th ed.Ch 51: Metabolic and Molecular Consequences of Dietary Restriction

    Time-restricted eating limits the daily eating window (often 8-10 hours), aligning with circadian rhythms. Alternate-day fasting and 5:2 alternate fasting and feeding days. Metabolic shifts include depleted glycogen, ketogenesis, and AMPK/SIRT activation. Clinical trials show comparable weight loss to continuous caloric restriction without superior cardiometabolic benefit, with adherence as the main predictor of success.

Related terms

AMPK, Caloric Restriction, Caloric restriction, Ketogenesis, Ketogenic Diet, Obesity