Chronic calorie-dense diet drives differences in motivated food seeking between obesity-prone and resistant mice.

Obesity results from overconsumption of energy, partly because of the inability to refrain from highly palatable rewarding foods. Even though palatable food is available to everyone, only a fraction of the population develops obesity. We previously showed that following chronic exposure to highly palatable food animals that gained the most weight also showed addictive-like motivation to seek for palatable food. An important question remains-is this extreme, addictive-like, motivation to consume palatable food the cause or the consequence of diet-induced obesity? Here, we show that obesity-prone (OP) mice exhibit higher motivation for palatable food consumption compared with obesity-resistant mice even before developing obesity, but that the full manifestation of this high motivation to eat is expressed only after chronic exposure to high-fat-high-sugar (HFHS) diet. HFHS diet also impairs performance in the operant food-seeking task selectively in OP mice, an impairment that persists even after 2 weeks of abstinence from HFHS food. Overall, our data suggest that while some aspects of food motivation are high in OP mice already before developing obesity, the chronic exposure to HFHS food accentuates it and drives the development of obesity.