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Obesity Weight Loss: Duodenal Switch Beats Gastric Bypass

Tim Boyer's picture

An obesity weight loss surgery comparison study between duodenal switch and gastric bypass was recently published stating that the duodenal switch method outperforms gastric bypass in weight loss. However, the study also showed that the duodenal switch surpasses the gastric bypass with adverse effects. While some health officials argue against the benefits of duodenal switch, others maintain that it may prove to be the best solution for the super-obese with a BMI of 50 and greater.

A high Body Mass Index (BMI) is a significant risk factor for morbidity from cardiovascular disease, diabetes and several forms of cancer. Individuals with a BMI of 30 or greater are considered to be obese. Changes in diet and exercise are the preferred measures to bring an individual’s BMI to below obesity levels. However, studies have shown that while dieting often leads to quick results initially, they are often temporary results that lead to an even greater BMI value than before dieting began.

As a result of diet and exercise not working for many cases of obesity, obesity surgery is becoming the preferred treatment for individuals who are considered “super obese” with BMI’s of 50 and greater - especially since recent studies have shown that bariatric surgery leads to sustained weight loss and can reverse some obesity-induced health problems. Approximately 5% of the U.S. population meets the requirements for obesity surgery.

In a recent study published in the medical journal Annals of Internal Medicine, researchers performed a comparison study between the popular gastric bypass surgery method and the less well-known duodenal switch surgery method. Their goal was to determine whether the duodenal switch method lead to a greater weight loss, more favorable improvements in cardiovascular risk factors and improved quality of life factors over the gastric bypass method.

The gastric bypass method (also referred to as “Roux-en-Y” gastric bypass surgery) accounts for approximately 80% of all the weight loss surgeries in the U.S. It consists of two parts: The first part is where the stomach is altered to create a small stomach pouch that can hold only about one cup of food. The second part is where the connection from the small stomach pouch bypasses the first part of the duodenum and goes further down the digestive tract directly to the jejunum. The result is that the patient can only eat small portions at a time with less calories being absorbed by the small intestine. On average, patients lose up to 60% of their pre-surgery weight.

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The duodenum switch method retains the original stomach and its connection (the pyloric valve) to the duodenum. The bypass is similar to the gastric method except it redirects pancreatic juices and bile separate from food passage until they all come together further down the digestive tract, which results in significantly reduced digestion time.

Some patients report that the duodenum switch method is favorable because it avoids losing the pyloric valve for an artificial connection (anastomosis) used in gastric bypass. Complications from a missing pyloric valve include blocking of the new bypass connection and “dumping syndrome.” Dumping syndrome is a rapid gastric emptying causing the small intestine to fill too quickly with undigested food. Dumping begins during or right after a meal and can cause symptoms of nausea, vomiting, bloating, diarrhea, and shortness of breath.

Both methods have common surgical problems such as leakage, bleeding ulcers, infections, etc.; but more importantly, both run a risk of malnutrition, anemia and osteoporosis because absorption of nutrients is significantly decreased. Supplements and blood tests are required for the rest of the patient’s life.

The comparison study consisted of 31 gastric bypass and 29 duodenal switch patients with BMI’s between 50 and 60 who were followed up two years after their surgery. Physical and biochemical measurements were made and the data statistically analyzed. What the researchers found was that the average BMI reduction from the duodenal switch method was 24.8 compared to 17.3 with the gastric bypass patients. This translated into an approximately 50-pound weight loss difference between the two methods with the duodenal switch method beating the gastric bypass method in weight loss.

However, the duodenal switch patients also experienced more medical health problems that the gastric bypass patients. Overall, participants in the duodenal switch group had almost twice the number of adverse events occurring from surgery: 10 of 31 (32%) after gastric bypass compared with 18 of 29 (62%) after duodenal switch. Three of the 29 duodenal switch patients developed protein malnutrition, two developed night blindness and one developed a severe iron deficiency that required an iron infusion.

The authors of the paper summarized their findings with the statement that weight loss is greater with the duodenal switch method and that both surgical methods result in significant and durable weight loss in super-obese patients with significant improvements in cardiovascular risk factors and health-related quality of life issues. An editorial comment states that patients can benefit from both types of bariatric surgery and that the choice between the two procedures should be individualized.

Source: “Weight Loss, Cardiovascular Risk Factors, and Quality of Life After Gastric Bypass and Duodenal Switch” Annals of Internal Medicine September 6, 2011 vol. 155 no. 5 281-291 http://www.annals.org/content/155/5/281.full.pdf+html?sid=4f58a04c-cf16-4559-a6de-058460ffaeef