Time of day differences in appetite and gut hormone responses to meal and stress challenges in adults with normal-weight and obesity

• Published in: Physiology & behavior 2022-10, Vol.254, p.113890-113890, Article 113890
• Main Authors: Carnell, Susan, Papantoni, Afroditi, Grillot, Charlotte L, Ungredda, Tatiana, Ellis, Stephanie, Mehta, Nandini, Holst, Jens J, Geliebter, Allan
• Format: Article
• Language: English
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/j.physbeh.2022.113890

•Postprandial appetite and ghrelin levels were higher in the PM vs. AM condition.•Gastric emptying was slower in the PM vs. AM condition.•Normal-weight adults showed altered glucose and GLP1 responses in the PM.•The obesity group showed lower post-stressor leptin levels in the PM vs. AM.•The normal-weight group showed an acute post-stressor decrease in PYY. Lifestyle factors like time of eating and stress exposure may impact physiology to promote excess weight gain. To understand behavioral and physiological mechanisms underlying these potential effects, we compared appetite and gut hormone responses to a series of meal and stress challenges beginning in the morning and the afternoon, in adults with normal-weight and obesity. Thirty-two adults (16 with normal-weight, 16 with obesity) underwent the same test protocol on different days, each following an 8 h fast. On one day the protocol began in the morning (AM condition); on the other day it began in the late afternoon (PM condition). On each day they first received a standardized liquid meal (9:00am/4:00pm), then a stress test (Socially-Evaluated Cold Pressor Test, 11:10am/6:10pm), then an ad libitum buffet meal (11:40am/6:40pm). Appetite and stress ratings were obtained, and blood was drawn for measures of ghrelin, PYY, GLP-1, insulin, glucose, cortisol and leptin. Acetaminophen was administered as a tracer to assess gastric emptying of the liquid meal. Across all three challenges, AUC cortisol was lower in the PM vs. AM condition (all p