Satiety associated with calorie restriction and time-restricted feeding: Peripheral hormones

Authors: TACAD, DEBRA - University Of California, Davis; TOVAR, ASHLEY - University Of California, Davis; RICHARDSON, CHRISTINE - University Of California, Davis; Horn, William; KRISHNAN, GIRI - University Of California, San Diego; Keim, Nancy; KRISHNAN, SRIDEVI - University Of California, San Diego

Submitted to: Advances in Nutrition
Publication Type: Review Article
Publication Acceptance Date: 2/11/2022
Publication Date: 2/22/2022
Citation: Tacad, D.K., Tovar, A.P., Richardson, C.E., Horn, W.F., Krishnan, G.P., Keim, N.L., Krishnan, S. 2022. Satiety associated with calorie restriction and time-restricted feeding: Peripheral hormones. Advances in Nutrition. 13(3):792-820. https://doi.org/10.1093/advances/nmac014.
DOI: https://doi.org/10.1093/advances/nmac014

Interpretive Summary: The prevalence of obesity is high in the US population, and more research is needed to understand why attempts for sustaining weight loss are often unsuccessful. In this review paper, we have summarized current knowledge of how hormones secreted by the organs in the gut and body fat tissue contribute to hunger, cessation of eating, known as satiation, and/or suppression of resuming food intake, known as satiety. We have compared and contrasted changes in these hormones associated with a restriction of caloric intake and a popular approach to dieting known as time-restricted feeding. We found that the hormone ghrelin, secreted by the stomach, may be different between these two forms of dieting. More research is needed, particularly with time-restricted feeding studies, to support this conclusion.

Technical Abstract: This review focuses on summarizing the current knowledge of how time-restricted feeding (TRF) and/or calorie restriction (CR) affect satiety mechanisms related to peripheral endocrine systems. This is part 1 of a two-part review, where part 2 discusses the central neuro-endocrine systems pertaining to the same question. CR is a common approach to inducing negative energy balance. Recently, TRF, which involves consuming food within specific time windows during a 24h day, has become popular owing to its relative ease of practice and potential to aid in achieving and maintaining a negative energy balance. TRF can be implemented intentionally with CR, or simply induce CR due to the time restriction. The effect of CR on satiety and neuroendocrine systems has been investigated, and an increase in the hunger hormone ghrelin, and suppression of satiety due to reduced fasting leptin, insulin, PYY, and CCK have been observed, some of these with stronger evidence than others. Following TRF, a reduction in fasting leptin, insulin, PYY and GLP-1 has been reported. In contrast to CR, fasting ghrelin was decreased in some TRF studies, while showing no change in others. In conclusion, the peripheral satiety systems appeared to be similarly affected by CR and TRF with few differences. Following TRF, the reduction in fasting GLP-1 implies reduced satiety while fasting ghrelin may not be as high compared to CR, implying less hunger. Studies that have evaluated metabolic effects of TRF are often short term, and only a few of them focus on food intake behaviors and the endocrine systems influencing them. Clearly, more evidence and studies addressing these aspects are needed.