How Sweet It Is: The Role of Taste Perception in Diet-Induced Obesity

Abstract

Our ability to taste sugar evolved to tell us that certain foods are good to eat because they provide us with energy. However, in the modern food environment of ubiquitous “added sugars”, this good taste can be hijacked in ways that cause overeating. This dissertation details the discovery of a means by which dietary sugar causes overeating in the fruit fly Drosophila melanogaster, via impairment of peripheral sweet taste sensitivity through increased intracellular glucose metabolic signaling by a conserved protein modifier. This in turn affects central value/motivational processing of the sweet sensation to alter feeding. We also present a new fly feeding assay, the optoFLIC, that is optimized for the monitoring and the closed-loop, optogenetic manipulation of long-term, steady-state feeding behaviors. Together, these findings depict a theory overeating that links excess dietary sugar with peripheral sensation and central reward, and they guide future research into the etiology and treatment of diet-induced obesity.