The first-pass metabolism (FPM) is a barrier to the toxicity of ethanol. Changes to the size and function of the stomach may alter FPM. Bariatric surgery, like the gastric bypass procedure, involves significant changes to the size and function of the stomach and leads to more rapid gastric emptying. Consequences will be faster absorption and higher peak concentration of ethanol after surgery than before. There are growing concerns that surgery for obesity in this way may cause alcohol abuse.

In this study the investigators compare changes in FPM of ethanol following two different bariatric surgical procedures.

Inclusion Criteria:

• volunteers from Central Norway
• morbid obese BMI > 40 kg/m2)
• morbid obese BMI > 35 kg/m2 given a obesity related disease that qualifies for bariatric surgery

Exclusion Criteria:

• previous or current alcohol abuse
• risk for alcohol harm as assessed by AUDIT
• alcohol abstinence
• liver disease except fatty liver, which occurs in more than 50% of those who seek bariatric surgery
• previous colon resection
• not/insufficiently able to informed consent
• drugs that interact with alcohol dehydrogenase
• drugs that slow down emptying of the stomach
• pregnancy

persons eligible for bariatric surgery in the Obesity policlinic, St Olavs Hospital, Trondheim, Norway