Alcohol and weight loss surgery: possible side effects [EXPLANATION]

Added by Klaudia Grabowska on 08.01.2021

Anyone who thinks seriously about losing weight with a surgery or regular diet knows that alcohol is a thing to avoid. Of course, the best solution is to cease drinking alcohol forever as it does more harm than good to us, however, we all know that it might be really difficult and hard, especially when there is a good occasion for it. So, in this article, we will explain all the aspects concerning alcohol and weight loss surgery that are important before, during, and after the process of weight loss. 

Alcohol before weight loss surgery

Weight loss surgery entails not only a diet regime afterward but also preparation before the surgery. In fact, all bariatric patients are provided with diet instructions for a few weeks before the surgery date. It is a high-protein and low-calorie diet, the main aim of which is to reduce fat around the main organs, especially the liver, and prepare the patient for lifestyle changes. Of course, alcohol is one of the forbidden substances in such a diet. 

size plus lady in red shirt looking and thinking

When the patient prepares for the bariatric surgery alcohol is forbidden for a few weeks before the surgery

When to stop alcohol before gastric sleeve or gastric bypass? Generally, drinking alcohol before weight loss surgery should be stopped as soon as possible, so preferably just after you make a decision that you will have the weight loss surgery or when you go on a diet. If you wonder why no alcohol before bariatric surgery is allowed, the reason is very simple. It contains many empty calories and absolutely no nutrients, also it can boost appetite and make you eat much more than usual. 

Alcohol use before and after bariatric surgery also differs. Before the surgery, alcohol is absorbed in the stomach, then released into the small bowel and finally, it goes to the bloodstream. Its effects are quite predictable for people. We rather realize how many drinks we need to think clearly, how many to get relaxed, and how many to lose control. So, drinking alcohol before bariatric surgery, e.g. drinking alcohol before gastric sleeve surgery, is not recommended due to its high calorific value and a bad influence on food choices and usually a glass of wine once in a while should do no harm at all, but after the bariatric surgery, the situation with alcohol gets more serious

Drinking alcohol after bariatric surgery

Can you drink alcohol after bariatric surgery? Yes, but you should introduce it gradually and with some modifications regarding alcohol types and amounts.

The main aspects of alcohol after bariatric surgery include:

  • metabolic changes – the bariatric surgery may inhibit alcohol absorption and make that patient feel intoxicated after a single drink; it may cause serious physiological and social problems;
  • low blood sugar level (hypoglycemia) – alcohol triggers glycogen depletion, which makes blood sugar level drops; the consequences of such a condition include nerve and brain damage or loss of consciousness; the post-op diet is a low-carb diet itself, so drinking alcohol after bariatric surgery would only escalate the problem with blood sugar level;
  • empty calories – obviously, alcohol is high in calories and does not have any nutritional value, so everyone who is on a diet should avoid it; drinking alcohol may not only stop weight loss but also trigger weight gain and bring post-op complications;
  • alcohol addiction – the prevalence of alcohol use disorders before and after bariatric surgery are noticed when patients have had some other addictions (mainly concerning food) before the surgery; the psychology likes replacing one addiction with another, so when people stop overeating, they tend to develop other habits, such as smoking or alcohol overuse; we strongly advise you to control yourself and prevent the development of any addiction after the surgery.
When the patient prepares for the bariatric surgery alcohol is forbidden for a few weeks before the surgery

Alcohol after gastric sleeve surgery may be dangerous due to the fact of how the surgery is complicated

Drinking alcohol after gastric sleeve

A gastric sleeve is a surgery that entails lifetime changes. Its role is to help and fasten weight loss, so patients should think about what they can do to maintain this process. Alcohol after bariatric sleeve surgery may be dangerous, so you should know when can you drink alcohol after gastric sleeve surgery and what amounts of alcohol after gastric sleeve surgery is acceptable. Gastric sleeve involves removing 75% of the stomach, which changes the acids production and food digestion. The enzymes that enable alcohol digestion are highly reduced, which means that undigested alcohol moves to the small bowel and blood. It makes an incredibly high risk of intoxication after tiny amounts of alcohol. Drinking alcohol after gastric sleeve surgery often causes nausea and vomiting – which is a sign that it should be stopped. Answering a straightforward question: Can I drink alcohol after gastric sleeve surgery? Yes, but during the first year after gastric sleeve when the diet is restricted and weight loss is rapid, patients must not drink alcohol at all. Only after a year, can you add a small amount of alcohol and check your body’s reaction to it. 

Drinking alcohol after gastric bypass surgery

Gastric bypass surgery is one of the most invasive weight-loss surgeries. It changes stomach size and affects food absorption. Alcohol after gastric bypass surgery is not absorbed properly and goes to the small bowel and bloodstream without a former intermingling. It is proven that drinking alcohol after gastric bypass surgery causes intoxication very fast, it also remains in the bloodstream for a long time. Thus, one of the worst effects of alcohol after gastric bypass surgery is an increased chance of an alcohol disorder – the brain starts to recognize tiny amounts of alcohol as a reward and pleasure and pushes patients to drink more often. 

So, can you drink alcohol after gastric bypass surgery? Yes, but as with gastric sleeve, only when the weight loss process ends and your weight is stabilized. Usually, it takes 1-2 years to lose excessive weight. After that time, you may check how your body reacts to alcohol intake, of course, these must be tiny amounts. Alcohol consumption after gastric bypass surgery must also be only occasional because otherwise you may gain weight again or develop serious health problems. 

Male friends having snacks while watching TV together

Alcohol itself does not cause weight gain, it is food eaten with alcohol that is not digested and turned into fat

Alcohol and weight loss

There is one important fact regarding alcohol and weight loss metabolism. Namely, alcohol itself does not cause weight gain – the body is not able to store alcohol or absorb it as body fat. However, alcohol prevents the body from fat burning. The body rather focuses on detoxification and any other metabolic functions are stopped. So, it is food eaten with alcohol that is not digested and turns into fat rather than alcohol itself. 

The general guidelines for alcohol drinking after weight loss surgery include:

  • avoid drinking alcohol for the first year after the surgery or during the whole weight loss period
  • once you can drink alcohol, refrain from drinking sugary drinks or carbonated beverages
  • remember that your stomach size is greatly reduced, so you can drink only tiny amounts of alcohol
  • you must not drive a car after drinking alcohol
  • never drink on an empty stomach, drink with meals to enable slow alcohol absorption
  • always think about the calories that alcohol contains
  • try not to drink regularly and do not treat alcohol as a tool to deal with your emotions or stress.

Calories in alcoholic drinks

Alcohol contains empty calories and has no nutrients at all, so if you want to lose or keep weight, you should add alcohol to the list of daily calorie intake. Below, we show how many calories in alcoholic drinks we can find:


Size / serving



150 ml120-150


about 350 ml200-250


45 ml100


45 ml100


45 ml100


45 ml100


45 ml110


about 100 ml220

Pina Colada

about 150 ml215

Long Island Ice Tea

standard drink 275

Dark ‘N’ Stormy

standard drink 185

We recommend that you choose low-calorie alcohol and if you mix it with other beverages, choose sugar-free drinks to reduce the number of calories.

Alcohol and weight loss surgery summary

When you have bariatric surgery, it does not mean that you cannot drink alcohol for the rest of your life. Once your excessive weight is lost, and you follow a healthy balanced diet, you can drink alcohol once in a while without any consequences. You just need to remember that your body’s reaction to food and drinks has changed, and you need to learn from scratch how much and what alcohol you can drink to feel good. Occasional drinking won’t do any harm to you and your weight, you just must have it under control and remember that you have made a great effort to lose weight, and it would be mindless to throw it away because of alcohol.  

cheers - happy people


“3 Myths About Alcohol & Bariatric Surgery.” 3 Myths About Alcohol & Bariatric Surgery | Advanced Surgical & Bariatrics of NJ,

Boyce, Written by Dr. Stephen, et al. “When Am I Able To Drink Alcohol After Bariatric Surgery?” Bari Life, 3 Dec. 2020,

“Can You Drink Alcohol After Weight Loss Surgery? – Penn Medicine.” – Penn Medicine,

Saareväli, Merle. “Drinking Alcohol After Bariatric Surgery ” Bariatric Services.” Bariatric Services, 17 Jan. 2020,

Siegfried, Donna. “Drug, Alcohol Deaths Soar After Weight-Loss Surgery.” WebMD, WebMD, 20 June 2019,–alcohol-linked-death-triple-after-weight-loss-surgery. 

Klaudia Grabowska

Klaudia started to work for Clinic Hunter many years ago, just after graduating from the John Paul II Catholic University of Lublin in Poland and since that time, this job has become her biggest passion and inspiration.

She has gained necessary expertise and experience by serving patients from all over the world (mainly the UK, Scandinavian countries, and the USA), taking an active part in numerous live and video trainings with clinics in Poland, Hungary and Turkey, participating in international medical tourism conferences and events, and completing internal Clinic Hunter courses. Now, Klaudia is an accomplished patient advisor specialising in such fields as dentistry, plastic and bariatric surgery and hair loss treatment. Her main idea is helping people nad making their lives better, that is why this job brings her so much satisfaction and joy.

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