The purpose of this study is to investigate potential metabolic effects of resveratrol in morbidly obese women undergoing gastric bypass surgery.

The investigators hypothesize that resveratrol will:

• Decrease hepatic very-low-density-lipoprotein-triglyceride (VLDL-TG) secretion
• Decrease hepatic and adipose tissue VLDL-TG uptake
• Increase insulin sensitivity

The investigators will look at changes in:

• Lipid turnover (VLDL-TG kinetics, palmitate kinetics,calorimetry)
• VLDL-TG uptake in different tissues (subcutaneous femoral adipose tissue, subcutaneous abdominal adipose tissue, visceral adipose tissue and liver tissue)
• Insulin sensitivity (glucose kinetics during hyperinsulinaemic euglycaemic clamp)
• Regulation of liver fat handling
• Lipoprotein lipase activity and fat cell size (abdominal and femoral adipose tissue)

Inclusion Criteria:

• Female
• 25-60 years
• Obesity (BMI > 35 kg/m2)
• Have at least one element of the metabolic syndrome either hypertension and/or hypercholesterolemia (high triglyceride, low HDL-cholesterol)
• Undergoing gastric bypass surgery
• Written informed consent

Exclusion Criteria:

• Any other relevant disease (e.g. diabetes, thyroid or parathyroid disease, heart, kidney or liver disease)
• May have arthrosis or depression
• Any present or previous malignancy
• History of smoking
• Alcohol dependency (more than 14 units of alcohol per week)
• Participation in studies with radioactive isotope within the last six months
• Hemoglobin under the normal range regarding to sex (under 7.3 mmol/l for women)