Disruption of white adipose tissue (WAT) homeostasis during obesity is central to the development of associated cardiometabolic complications. Dietary supplementation with oleic acid in obese patients can limit these complications. Experimental data, obtained in preclinical models, suggest that the beneficial effects of oleic acid may protect the TAB by increasing cholesterol esterification. The NAMICO study aims to test this hypothesis using TAB biopsies collected from obese patients undergoing bariatric surgery who had previously undergone dietary enrichment with either a conventional oil or an oil rich in oleic acid.

Inclusion Criteria:

• • Individual who has given informed consent.

  • Female adult aged between 18 and 60 years (included).

  • Patient with obesity at inclusion, meeting the HAS criteria for bariatric surgery eligibility: BMI ≥ 35 kg/m² associated with a comorbidity or BMI > 40 kg/m².

  • European origin: For this pilot study, we need to reduce variability factors and focus the research on women of European descent only (having both parents identified by the patient as of European origin).

  • Effective contraception if sexually active, or abstinence, or menopause (criterion required for bariatric surgery).

  • Presenting at inclusion with at least two clinical criteria of insulin resistance according to the definition of the International Diabetes Federation (IDF):

    • Dysglycemia (fasting glucose ≥ 100 mg/dL, glucose intolerance, or type 2 diabetes).
    • Hypertension (≥ 130/85 mm Hg).
    • Low HDL-cholesterol (< 50 mg/dL).
    • Elevated triglycerides (≥ 150 mg/dL).

  • Affiliated with a social security system or a beneficiary of such a system.

  • Bariatric surgery performed at Nantes University Hospital (CHU de Nantes).

Exclusion Criteria:

• • Modification of diabetes treatment within the past month.

  • Ongoing or planned insulin therapy before bariatric surgery.

  • Modification of lipid-lowering treatment within the past three months.

  • Systemic corticosteroid therapy.

  • Antiviral therapy (HIV).

  • Dietary supplementation affecting lipid metabolism, including proactive margarine, Danacol, polyunsaturated fatty acid supplementation, or any other substance identified by the investigator.

  • Exocrine pancreatic insufficiency.

  • Pregnancy or breastfeeding.

  • History of organ transplantation.

  • Individual deprived of liberty or under legal protection (guardianship or trusteeship).

  • Any clinical condition in which the investigator considers that inclusion in the study may harm the patient's health or compromise the proper conduct of the study.

  • Participation in other clinical trials, except for non-interventional studies and research on surgical techniques or postoperative strategies.

    • Type I, monogenic or secondary diabetes.

Oil bottles will be numbered in accordance with a correspondence list generated electronically by the datamanager (blinding procedure for participant, investigator and their team).