Protocol for evaluating protein intake-induced feeding inhibition in Drosophila using a pre-feeding approach

Consumption of dietary protein has been shown to elicit the strongest satiety among macronutrients. Protein intake-induced feeding inhibition (PIFI) plays a critical role in the maintenance of nutrition homeostasis. Here, we present an optogenetic pre-feeding protocol for studying the neural mechanisms underlying PIFI in Drosophila. We describe steps for preparing and loading flies into feeding chambers, quantifying food consumption, estimating excretion levels following the feeding test, and evaluating the inhibitory effect of dietary protein. For complete details on the use and execution of this protocol, please refer to Li et al. and Sun et al.¹^,².