What’s the difference between gastric bypass and sleeve?

FlyToTreat/Articles/ What’s the difference between gastric bypass and sleeve?

An increasing number of people are considering weight loss surgery to be fit and healthy. There are so many kinds of weight loss surgeries. Gastric sleeve and gastric bypass surgery are a kind of bariatric surgery that is famous and effective for people. These two surgeries have a lot of similarities and some differences. Both are permanent, leading to the highest percentage of weight loss and reducing hunger. In this article, we will talk about the difference between gastric bypass and sleeve surgery. To compare these two, we should consider a lot of data. But keep in mind that your surgeon is the best person to choose the best kind of surgery for you.

These are two common types of bariatric surgery that lead to weight loss to a great extent. Although the base of these two surgeries is different, and there is a difference between gastric bypass and sleeve, the result is the same. These surgeries work in two ways: one way includes pulling the stomach very quickly, and the patient eats less amount of food. Another way is by reducing the hunger hormone known as ghrelin. Gastric sleeve surgery is a permanent way to reduce the size of a stomach. This surgery can cut about 80 percent of the stomach. Just a tiny banana-shaped stomach pouch can remain. In gastric bypass surgery, the way is entirely different. The surgeon removes most parts of the stomach and the first part of the small intestine. Then departure of the remaining stomach would be connected to the remained part of the intestine. So, the acid and the digestive enzyme will be produced by the part of the stomach which remains. The essential part of this surgery is that the part of the intestine is responsible for absorbing nutrients and calories. Due to the fact that this part is cut, most calories patients eat can’t be absorbed. Consequently, weight loss can be seen. But the problem is that the high percentage of nutrients can’t be absorbed, so the patient needs to take supplements.

What is the difference between gastric bypass and gastric sleeve?

In this part of the article, we will talk about many factors that can make differences between these two effective surgeries and answer patients' questions about these two kinds of surgeries.

Amount of weight loss after surgery

One critical difference between gastric bypass and sleeve is the amount of weight loss after surgery. Many patients need to know what kind of surgery helps them to lose weight at a rapid pace. First, you should know that without a change in your lifestyle, your habits can’t change the results of surgery. So, the most critical factor is what to do and eat after surgery. But between these two, we should say that patients usually lose 60 to 80% of their excess body weight in a year after gastric bypass.

On the contrary, when it comes to gastric sleeves, weight loss during two years is between 50 to 70% of excess body weight. Gastric bypass is the best surgery for patients with a BMI over 45. not only it produces more weight loss on average, but also it creates dumping syndrome. Dumping syndrome is the feeling that a patient can get, which includes sweating and general illness. This syndrome happens when patients eat many sweet carbohydrates, fast foods, fried foods, or other harmful foods. So, the question is why the syndrome can positively affect people. The answer is that patients feel like they are unable to eat these foods, which can have adverse effects on their feelings.

The speed of weight loss can have positive and negative effects. The positive impact is that a patient feels healthier and can lead a healthy and happy lifestyle. It’s easier to exercise and continue healthy habits. In comparison, when a patient loses weight over two years, the chance of saggy skin and stretch marks will reduce to a great extent.

The difference between the benefits and the drawbacks of gastric bypass and sleeve

Patients need to be aware of the advantages and disadvantages of these weight loss surgeries. So, in this part, the benefits and drawbacks will be discussed.

The benefits of gastric bypass surgery

When it comes to talking about the difference between gastric bypass and sleeve surgery, talking about their benefits is required. The surgery has been done for several years in all the countries in the world. So, the surgeons and the patients are more familiar with the complication risks and other factors related to this surgery. A lot of studies have researched the benefits of this surgery, so patients would be more likely to do this surgery.

Patients suffering from acid Reflux should undergo gastric bypass surgeries since it has a lower risk of Reflux disorder.

It increases the chance of dumping syndrome. Although it seems very bad, complications of the surgery it is not. It’s the best way to lose weight.

What are the benefits of dumping syndrome?Dumping syndrome occurs when the atomic is empty as fast as possible. The body responds to these actions. After bypass surgery, the chance of dumping syndrome would be increased. When a patient experiences the first symptom of dumping syndrome, the body doesn’t like that. So, the mind has control of your body and orders you not to eat to prevent experiencing the bad symptoms of this disease. Patients’ food to be released, and not eating more carbohydrates would lose more weight. This reminder and negative reinforcement help curb the consumption of less healthy foods.

The benefits of gastric sleeve surgery

The amount of weight loss in this surgery is lower than other types in the first year, so patients lose weight at a slow pace, and the chance of saggy skin can be low.

Due to the reduction of the hunger hormone, patients have no hard feelings for not eating food, and, emotionally, patients have no problem.

Risk of complications

Another crucial difference between gastric bypass and sleeve is the risk of complication. These factors should be taken into account by the patient since two complications are not limited to the surgery, but one year after surgery, you can see some complications. Although mortality or the risk of death is under 1%, other complications exist.

Some factors that can be seen after any surgery, including bariatric surgery, include hemorrhage, deep vein thrombosis, pulmonary embolism, side effects of general anesthesia, leakage of stomach fluid, infection of your incision, postoperative pain, gallstones, pneumonia, nutritional deficiencies, such as vitamin deficiencies, constipation, dumping syndrome and saggy or loose skin.

Possible complications of gastric bypass surgery

In this part of the article about the difference between gastric bypass and sleeve, we will discuss all the most essential complications of gastric bypass surgery.

  1. Nausea

One of the gastric bypass complications is nausea; the average chance of this complication is about 70%. However, there are simple ways to control nausea after this surgery. Please talk to your doctor about your diet and follow their recommendations.

  1. Dehydration

Another side effect of gastric bypass surgery is dehydration. The risk of this complication is about 65% or more. By drinking enough water, about 2 liters a day, the chance of dehydration would be as low as possible. Severe dehydration can cause vomiting, which can lead to other problems.

  1. Indigestion

Indigestion is defined as when a person is not able to digest food. It can cause problematic issues for patients. So, it should be treated as soon as possible. Some ways include drinking liquid for a certain amount of time or taking anti-acid and H2 blockers. Another way is changing dietary patterns.

  1. Reactive hypoglycemia

This complication results from an imbalance between blood sugar and insulin within the bloodstream. Another difference between gastric bypass and sleeve is this complication. It can occur minutes after eating carbohydrates. In this situation, when the body has used carbohydrates, the insulin remains higher. So, it can cause low blood sugar. This complication can be a result of excessive dumping syndrome after bypass surgery. In severe cases, surgical removal of a portion of the pancreas may be required.

  1. Nutritional deficiencies

This complication is very common after surgery, no matter the type. The complication can be anemia, metabolic bone disease, or osteoporosis. It can be solved by taking multivitamins and mineral supplements.

  1. Marginal ulcers

This complication is common after gastric bypass. It can be easily avoided by having the best dietary guidelines, not smoking, and not using NSAIDs (such as ibuprofen). It can be confirmed by endoscopy. For trading, this problem usually causes antacids to work very well.

Other Complications specific to gastric bypass include stomach perforation, increased sensitivity to alcohol, bowel obstruction, and stomach ulcers.

Complications of gastric sleeve surgery

The most significant risks and complications of gastric sleeve surgery will be discussed in this part. Overall, this surgery is safe, and the chance of complications is rare.

  1. Gastroesophageal reflux disease (GERD)

Gastroesophageal reflux disease (GERD) is the most common complication of gastric sleeve surgery. Another difference between gastric bypass and sleeve is this complication. It can be seen very high among patients. It often leads to histopathologic changes and microscopic structural changes in the esophagus. It may also lead to esophagitis, which is an inflammation of the esophagus.

With a proton pump, inhibitors can be used to treat this complication. In the case of symptoms persisting, a gastroscopy (which is an examination of the esophagus, stomach, and duodenum using an endoscope) is performed.

  1. Nutrition deficiency

It’s common after weight loss surgery, and for most patients, taking supplements can treat this problem.

  1. Stricture (chronic)

Chronic strictures are difference between gastric bypass and sleeve surgery. This complication requires endoscopic or surgical treatments. The length of narrowed portion can affect the way of treatment. Endoscopic dilatation is used in the case that narrowing is short. However, surgery is often necessary if the narrowing is long and endoscopic dilation fails.

  1. Stricture (Acute)

Although this complication is seen more in gastric bypass, it can also be seen after gastric sleeve. Treatment is accomplished by not consuming food orally and rehydration with IV fluids. Endoscopic dilation is also performed occasionally on gastric sleeve patients with this condition.

  1. Staple line failure

Another critical side effect that is the immediate concern of surgery is staple line failure. Although the chance of this side effect is about 2.4 percent, it should be considered by surgeons. When it fails, an increase in heart rate and body temperature and breathing problems can be experienced by patients. If it happens a few days after surgery, can repair it through laparoscopy.

Complications specific to gastric sleeve surgery include narrowing along the stomach pouch and stomach obstruction.Read more about gastric sleeve side effects.

What are dietary changes after these surgeries?

Another aspect that can be the difference between gastric bypass and sleeve is dietary change. Most patients' dietary changes would be the same after gastric sleeve and gastric bypass surgery. For the first month, you should drink liquids and not eat food. After that, you would be allowed to eat pureed and soft food. After six weeks, you could eat food like other people worldwide. Some essential guidelines required for you after gastric sleeve or gastric bypass surgery include chewing your food thoroughly, eating small amounts and stopping when you’re full, eating slowly, staying hydrated by drinking enough water, taking the recommended vitamins and supplements, sipping fluids rather than drinking quickly, avoiding carbonated beverages and avoiding food that’s difficult to digest.

What is the difference between the size of stomach in theses surgeries?

The most critical difference between gastric bypass and sleeve is the stomach size after surgery. The stomach size after gastric bypass surgery would be smaller than a golf ball. However, the stomach size after gastric sleeve surgery is about two or five ounces of food. The stomach size in gastric bypass is smaller than the sleeve, and patients feel full after eating less food. In both surgeries, the stomach size can be increased over time. If patients don’t be careful about their diet, their stomachs in both ways can be starched, and patients experience weight gain after a while.

What’s the difference between the cost of a gastric sleeve and gastric bypass surgery?

Another difference between gastric bypass and sleeve is the cost. The cost of these surgeries can be different from one country to another. The geographical location, the type of surgery, and complications during surgery can include this surgery's cost. Due to the fact that the gastric bypass is more involved, the cost of it can be more than a gastric sleeve surgery. But it’s not the rule and can be different in some parts of some countries. If you are interested in doing your surgery in the cheapest country for gastric sleeve surgery, Iran is the best place. The surgery cost can be as low as possible, and you have no problem.

What is the difference between nutrient absorption in these surgeries?

Nutrient absorption is another difference between gastric bypass and sleeve. Due to the fact that in gastric bypass surgery, a small amount of a small intestine is cut, the ability to absorb nutrients is not the same after surgery. On the contrary, the absorption of nutrients remained unimpaired by gastric sleeve surgery. So, the amount of food the patient eats can be absorbed in the body, and there is no problem, but in bypass, the patient must take supplements for the rest of their lives.

Associated health conditions

Another difference between gastric bypass and sleeve is the improvement in health conditions. Gastric bypass surgery would be more effective for patients suffering from weight-related diseases such as hypertension and sleep apnea. This is because the amount of weight loss in one year after gastric bypass surgery is enormous and more than gastric sleeve surgery. So, it can help patients get rid of these diseases very soon after surgery and start exercise and healthy habits.

The recovery times after these two types of surgeries

The recovery time is another difference between gastric bypass and sleeve. Considering that gastric bypass is more complicated and has two types of surgeries, it can take more time for patients to recover and be treated after surgery. But after gastric sleeve surgery, patients need less recovery time and can do everyday activities. This aspect is essential for many patients since they are seeking surgery so they can go to work after less time.

The amount of hunger

Since the left side of the stomach is cut in gastric sleeve surgery and this area is responsible for the Hunger hormone, this surgery patients can experience less hunger than patients who have had gastric bypass surgery. This is another difference between gastric bypass and sleeve. Although the patients after bypass gastric surgery experienced hunger as well as gastric sleeve, the hunger reduction in gastric sleeve patients is Much more than in other patients. Some of them say that they don’t have a feeling for food. So, somebody should tell them to eat for six months after surgery.

 What can FlyToTreat do for patients?

 FlyToTreat is one of the most influential agencies in bariatric surgeries especially in Iran (read more about gastric sleeves in Iran.) We can help patients with weight loss with fewer risks and complications. Our surgeons and surgery team will allow patients to choose the best surgery type for their benefit regardless of the difference between gastric bypass and sleeve surgery. If you are eager to lose weight, ask us any questions that are on your mind.


Although there is some difference between gastric bypass and sleeve surgery, there are two types of good bariatric surgery that can lead to weight loss for patients who are suffering from weight-related diseases because of a BMI over 35. You should remember that choosing the type of surgery is your surgeon’s responsibility. Knowing about these surgeries, their complications, risks, and recovery is good. Still, your surgeon would choose the best type of surgery for your body based on your current weight, medical history, expectations, weight loss goals, health condition, and personal preferences. The surgeon and the place you choose for this surgery matter. Since the surgeon plays an essential role in the type of surgery you are doing and the result you will get. Your surgeon should monitor your personal habits and your lifestyle.

Regarding the difference between gastric bypass and sleeve surgery, we can tell you gastric bypass surgery can help you lose more weight and result in quick weight loss. It’s irreversible. Less likely to cause a reflux disorder and reduce the absorption of many calories. Regarding gastric sleeve surgery, we should tell you that it has a lower risk of complications and a faster recovery time. It is less likely to cause dumping syndrome because of fewer issues with nutrient absorption. It’s appropriate for certain high-risk medical conditions, it is less likely to require follow-up procedures, and it is irreversible.


AUTHOR: FlytoTreat's team of Authors

17 June 2023 - Updated At: 13 May 2024