More than 50,000 patients in France benefit from bariatric surgery every year. However, nutritional complications (protein malnutrition, hypoglycaemia) are common and primary or secondary weight failures (weight recovery) account for almost 20% of operated. Weight loss and the metabolic effects of surgery are not related only to a reduction in dietary intakes, but also to mechanisms independent of caloric reduction, such as eating behaviour after bariatric surgery (Gastric Bypass or sleeve gastrectomy). These choices are guided by perceived changes in the properties of the food, resulting in changes in tastes, palatability and more generally food preferences. Among available tools to evaluate dietary preferences we selected the Food Leeds Preference Questionnaire (FLPQ) to assess those modifications. During this test, photographs of food products classified according to predetermined characteristics are presented with different instructions and response design to estimate liking, wanted for food, implicitly or explicitly. Our main hypothesis is that the use of the Food Leeds Preference Questionnaire will highlight differences in dietary preferences according to the type of bariatric surgery performed.

We will be conducted a study observational study on three parallel groups: a control group composed of patients suffering from unoperated obesity, a group of patients operated for a sleeve gastrectomy and a group of patients operated for a gastric bypass. We will include 45 patients per group. The patients will have to pass the Leeds Food Preference Questionnaire (LFPQ). Our judgment criterion will be the degree of food preference assessed using the LFPQ. Participants will also be assessed on behavioural parameters with the Binge Eating Scale, the Yale Food Addiction Scale Version 2.0 and the Urgency, lack of Premeditation, lack of Perseverance and Sensation seeking Impulsive behavior scale (UPPS-P) short version.

Inclusion Criteria:

• Patient, male or female, between 18 to 65 years old
• Patient with a BMI between 18.5 and 60 kg / m2: minimum 35 kg / m2 for the obesity group
• Patient undergoing initial assessment before bariatric surgery for the obesity group
• Patient being assessed for follow-up after bariatric surgery (after sleeve gastrectomy or gastric bypass)
• Patient agreeing to participate in the study.
• Patient affiliated to a Social Security scheme or beneficiary of such a scheme

Exclusion Criteria:

• Patient with other psychiatric comorbidities, including a bipolar mood disorder or eating disorder
• Patient with food eviction, whether medical or cultural
• Patient with ongoing psychotropic treatment (except anxiolytic treatment)
• Patient unable to give his agreement, not mastering the French language,
• Patient under authorship or curators

This study will focus on a population of patients who are or have been obese and are being cared for at the Lyon Sud Hospital Center. Patients will either be undergoing initial assessment or being assessed for follow-up after bariatric surgery (after sleeve gastrectomy or gastric bypass).