BaRiatric Surgery AnD FRUctose Handeling In Obese subjecTs

To investigate whether changes in fructose dietary intake can help to improve dietary fructose-induced insulin resistance and post bariatric weight loss in obese subjects of Caucasian descent

Inclusion Criteria:Scheduled for a RYGB gastric bypass*Men and premenopausal women > 18 years of ageCaucasian descentAbility to provide written informed consent* All subjects on the waiting list meet the criteria for bariatric surgery, that is:BMI > 40 kg/m2 OR >35 kg/m2 with obesity related co-morbidityReasonable supervised attempts to lose weightExclusion Criteria:Unstable metabolic condition defined as;Diabetes with poor glycemic control (HbA1c > 8.5%);Use of an antidiabetic or anti-obesity drug;Malabsorptive or restrictive bariatric (weight loss) surgery in historyEvidence for a form of liver disease (except for NAFLD without cirrhosis)Known genetic basis for insulin resistance or glucose intoleranceUse of certain drugs known to produce hepatic steatosis in the previous 6 months (such as oral corticosteroids, high-dose estrogens, methotrexate, tetracycline, amiodarone)Malabsorptive disease orders (celiac disease, inflammatory bowel disease)Use of certain drugs that may injure the lining of the intestine in the previous months (colchicine, cholestyramine)Excessive alcohol intake (≥5 IU per day or ≥ 14 IU per week)Recent use of antibiotics (≤ 3 months before surgery)Hemostasis disorders or current treatment with anticoagulants Any primary lipid disorderUnable to maintain diet intervention, or unable to reliably rapport diet