It is well known that the state of hunger can modulate hormones and hypothalamic neural circuits to drive food-seeking behavior and consumption. While the olfactory sense is critical to foraging, the role of the olfactory cortex in regulating food learning and preference is unclear. The anterior piriform cortex (APC) is located one synapse downstream of the olfactory bulb and is an important olfactory structure for odor discrimination, perception, and memory. Here, we investigated whether acute fasting in mice can alter an odor-guided foraging behavior and how it can alter neurons and synapses in the APC. Acute fasting enhances the motivation of a mouse to search for food pellets and increases food intake. Performing this foraging task strongly activates the APC, accompanied by an increase in structural excitation–inhibition ratio in synapses. To examine the effects of fasting on learning about a new food substance, we developed a learning paradigm where acutely fasted lab mice were exposed to a new food (peanut butter; PB). Before learning (training), naïve mice preferred to eat the familiar chow compared to PB when given a choice. In contrast, after learning, the trained mice showed increased preference towards PB compared to food chow. Chemogenetic inhibition of the APC prevented the mice from acquiring this learned preference for PB. These results illuminate the role of an olfactory region, APC, in food foraging and learning of novel food substances. Our findings will pave the way for discovering neural circuits that link sensory information to control feeding behavior.