Wild animals perceive a wide range of external stimuli and respond appropriately. They also sense internal bodily states, such as hunger, and adjust their behavior accordingly. Our research focuses on how animals respond to both internal and external cues related to feeding behavior. Using two model organisms—fruit flies and mice—we investigate how the gut, brain, and microbiome interact to detect nutrients and drive feeding behavior through neural mechanisms. In fruit flies, we study how various nutrients—ranging from macronutrients such as carbohydrates and proteins to micronutrients such as sodium and vitamin C—are sensed after ingestion and how these signals alter behavior. Based on these findings, our goal is to uncover analogous nutrient-sensing mechanisms in mice. In addition, we are currently examining how interactions along the gut–brain–microbiome axis influence neurological diseases such as Alzheimer’s and Parkinson’s disease in mouse models.