The risk of alcohol use disorder was twice as high for people who had gastric bypass than for those who had placement of an adjustable stomach band. Although the researchers were not sure why there was such a difference, it does make sense.
The stomach lining contains an enzyme called alcohol dehydrogenase that breaks down alcohol. With a much smaller stomach after gastric bypass, less of this enzyme is available and more alcohol gets directly into the blood stream. Also, alcohol remains at higher concentrations for longer periods after gastric bypass.