High-fat diet exposure, internal state, and reward value influence decision making during motivational conflict

Survival depends on adaptive decision-making wherein the benefits of seeking food are weighed against the risk of threats, a process influenced by internal states like hunger. Highly palatable, calorie-dense foods, such as a high-fat-containing diet (HFD), potently drive feeding even in the absence of hunger. However, it remains unclear whether approach-avoidance conflict is shaped by the interaction between hunger state, motivation for rewards of differing palatability, and the lasting effects of chronic high-fat diet exposure (cHFD). Here, we examined how hunger, reward value, and cHFD exposure affect behavioral strategies for resolving approach-avoidance conflict. We established a modified platform-mediated avoidance (PMA) task where mice resolve conflict between approaching a reward and avoiding a footshock. In this task, we systematically manipulated three key variables: (1) hunger state [via 6-hour (6h) vs. 23-hour (23h) food restriction], (2) reward type (sucrose vs. a high-fat liquid (HF-reward)), and (3) diet history (cHFD vs. control diet). We found that hunger, reward value, and diet pre-exposure shaped conflict resolution. Hunger increased risk-taking, with 23h food-restricted mice seeking more rewards than mice with limited 6h food restriction. Similarly, HF-reward increased approach behavior even under 6h food restriction. Importantly, cHFD pre-exposure robustly suppressed reward-seeking during conflict, overriding the motivational effects of both hunger and acute reward value. These findings highlight the interaction between internal states (e.g., hunger), reward value, and environmental factors (e.g., diet) in shaping behavior during conflict.