Acute Effects of High-protein and High-fat Isoenergetic Meals on Total Ghrelin Plasma Concentrations in Lean and Obese Women

Introduction

The recent discovery of ghrelin has led to a new understanding of the physiology that governs energy homeostasis and the mechanisms of feeding and satiety. Ghrelin is a 28-amino-acid peptide that is mainly produced in the gastric fundus, and in other tissues in smaller amounts [1]. It was first characterized as a potent growth hormone (GH) secretogogue [2]. Soon, though, it became apparent that ghrelin is a powerful orexigenic hormone that acts through activation of neuropeptide Y (NPY) and agouti-related protein (AGRP) neurons in the arcuate hypothalamic nucleus [1]. Its levels rise sharply just before feeding and drop quickly afterwards, a fact that points to its pivotal role in meal initiation and termination, respectively [3]. While ghrelin plasma levels have been found to decrease following a fat-rich diet in rats [4], the data on the acute effect of meal composition, especially of fat-rich meals on postprandial ghrelin levels in humans are scarce.

In a previous publication [5], we showed that a fat-rich meal fails to suppress ghrelin levels in both lean and obese individuals in contrast to a carbohydrate-rich meal, which suppresses ghrelin concentrations in lean but not in obese individuals.

In the present study, we examined the possible differences in the postprandial ghrelin levels of lean and obese women after two isoenergetic meals of different composition - one rich in protein and one rich in fat.

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