Cheers! The Science Behind Alcohol Consumption Post-WLS

Article By: Maria Tucker, MPH, RDN, LDN, CDCES

Maria Tucker is a Registered Dietitian and Certified Diabetes Educator with over 20 years of experience assisting patients with diabetes, obesity, and nutrition-related conditions. Maria is also the Founder of, a site dedicated to healthy recipes and kitchen shortcuts.

Bariatric surgery has been proven to provide successful long-term treatment for obesity and improvements in obesity-related diseases. However, there is now more evidence showing bariatric surgery patients, in particular those who have undergone Roux-en-Y gastric bypass, are at an increased risk of developing new-onset alcohol use disorder (AUD) or relapsing into it after a long period of abstinence from or decreased use of alcohol, especially during the first year post surgery.

Alcohol use is a part of the nutrition and psychological evaluation and education before and after surgery. Patients are encouraged to decrease alcohol use before surgery and instructed to avoid alcohol use for 6 months or for 1 year post surgery, depending on the bariatric surgery program. Providers know that not all patients adhere to this recommendation and do indulge in alcohol during the first year after their surgery. Why is it recommended that alcohol be avoided after surgery? How does it affect someone who has undergone gastric bypass surgery?

According to the 2016 position statement of the American Society for Metabolic and Bariatric Surgery (ASMBS), gastric bypass surgery is associated with accelerated alcohol absorption, higher maximum alcohol concentration, longer time to eliminate alcohol in both men and women, and increased risk of developing AUD.

The stomach contains alcohol dehydrogenase, an enzyme that breaks down or neutralizes alcohol which contributes to the rate of eliminating alcohol from the blood. When the stomach is reduced in size, such as in gastric bypass surgery, alcohol comes in contact with less alcohol dehydrogenase, resulting in more alcohol entering the bloodstream and then quickly distributed throughout the body. In addition, the smaller gastric bypass stomach results in a more rapid movement of alcohol to the small intestines where about 80% of the alcoholic beverage is absorbed. This leads to a higher peak bodily alcohol content (BAC), meaning a higher alcohol level in the body compared to someone who did not have gastric bypass. Another thing to think about is how long it takes for the body to eliminate alcohol or reach zero BAC. For many post surgery patients, a single alcoholic drink can lead to a high enough blood alcohol level to be considered legal intoxication.

In addition to higher and quicker rate of intoxication, alcohol consumption after bariatric surgery can cause an increased risk of low blood sugar, due to decreasing the concentration of glucose in the blood. The liver, which normally helps maintain stable blood sugars by storing it and releasing sugar when needed, such as between meals and while you sleep, will opt to metabolize the alcohol over maintaining blood sugar. This can lead to low blood sugar. It is important to monitor for symptoms of low blood sugar or hypoglycemia, such as confusion, loss of balance, shakiness, feeling faint, blurred vision, or palpitations.

Finally, wine and spirits are typically low in carbohydrates (except for mixed drinks and cocktails made with sugary syrups or juice) but are sources of empty calories which can result in weight loss slowing down or even weight regain. For patients already experiencing slow weight loss or weight plateau, drinking alcohol can make an already frustrating situation worse.

To be safe, it is wise to think about the consequences of drinking alcohol if you’ve had gastric bypass surgery before consuming it. Ask yourself... Is it worth it?

BariMelts provides general recommendations, not to be construed as medical advice. Please consult your doctor.

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