Effects of Short-term Fasting on Ghrelin/GH/IGF-1 Axis in Healthy Humans: The Role of Ghrelin in the Thrifty Phenotype

Abstract

Context: A greater decrease in 24-hour energy expenditure (24hEE) during short-term fasting is indicative of a thrifty phenotype. Objective: As ghrelin and the growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis are implicated in the regulation of energy intake and metabolism, we investigated whether ghrelin, GH, and IGF-1 concentrations mediate the fasting-induced decrease in 24hEE that characterizes thriftiness. Methods: In 47 healthy individuals, 24hEE was measured in a whole-room indirect calorimeter both during 24-hour eucaloric and fasting conditions. Plasma total ghrelin, GH, and IGF-1 concentrations were measured by enzyme-linked immunosorbent assay after an overnight fast the morning before and after each 24-hour session. Results: During 24-hour fasting, on average 24hEE decreased by 8.0% (P