A lot of evidences defend the existence of a relationship between industrial food consumption and the increase of obesity prevalence (OMS, 2011). Our study explored the impact of Western diet exposure on both cognitive and hedonic functions through behavioural assessments and brain imaging, completing by metabolic and physiologic assessment, to determine the role of diet, then, weight gain, on the cognitive abilities, eating behaviour and metabolism of adult males and females Yucatan minipigs, before and after diet induced obesity challenge. Learning and memory performances were tested using the holeboard discrimination task, with a palatable food reward (M&M’s®). Eating behaviour was explored with a two-choice feed test. In parallel, the brain glucose metabolism was investigated using Positron Emission Tomography (PET), during a sucrose oral stimulation. This longitudinal study involves three steps : the first one aims to compare an HFF (hight fat fructose) to a STD (standard) diet, with isocaloric incomes. The second one consisting in an obesogenic challenge with ad libitum access to HFF food. The third step involves weight loss, using bariatric surgery or restrained diet. Key words: nutritional imprinting, behavior, brain, reward system, memory, learning, minipigs