A scoping review of intermittent fasting, chronobiology, and metabolism

• Published in: The American journal of clinical nutrition Vol. 115; no. 4; pp. 991 - 1004
• Main Authors: Santos, Heitor O, Genario, Rafael, Tinsley, Grant M, Ribeiro, Poliana, Carteri, Randhall B, Coelho-Ravagnani, Christianne de Faria, Mota, João F
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2022; Oxford University Press; American Society for Clinical Nutrition, Inc
• Subjects: alternate-day fasting; Animals; Biological clocks; Blood Glucose; Body weight loss; cardiovascular disease; chrononutrition; Circadian Rhythm; Circadian rhythms; Clinical nutrition; Clinical trials; diabetes; Diet; Eating; Fasting; Humans; intermittent fasting; Lipids; Meals - physiology; Metabolism; Nutrition; Nutrition therapy; obesity; Synergism; time-restricted eating; time-restricted feeding; Weight loss; Weight Loss - physiology; EE; FFA; cardiovascular disease; T2DM; time-restricted eating; RCT; weight loss; TRF; FBG; eTRF; time-restricted feeding; DIT; chrononutrition; TC; WMD; intermittent fasting; AMPK; alternate-day fasting; diabetes; IF; obesity
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/nqab433

Chronobiology plays a crucial role in modulating many physiologic systems in which there is nutritional synergism with meal timing. Given that intermittent fasting (IF) has grown as a flexible dietary method consisting of delayed or early eating windows, this scoping review addresses the effects of IF protocols on metabolism as they relate to clinical nutrition and the circadian system. Although nocturnal habits are associated with circadian misalignments and impaired cardiometabolic profile—and nutritional physiology is better orchestrated during the day—most findings are based on animal experiments or human studies with observational designs or acute meal tests. Well-controlled randomized clinical trials employing IF protocols of delayed or early eating windows have sometimes demonstrated clinical benefits, such as improved glycemic and lipid profiles, as well as weight loss. However, IF does not appear to be more effective than traditional diets at the group level, and its effects largely depend on energy restriction. Thus, efforts must be made to identify patient biological rhythms, preferences, routines, and medical conditions before individual dietary prescription in clinical practice.