Gastric Bypass Surgery changes food preferences

Gastric bypass surgery alters people’s food preferences so that they eat less high fat food, according to a new study led by scientists at Imperial College London. The findings, published in the American Journal of Physiology—Regulatory, Integrative, and Comparative Physiology, suggest a new mechanism by which some types of bariatric surgery lead to long-term weight loss.

A growing number of obese patients are choosing to undergo bariatric surgery in order to lose weight, with over 7,000 such procedures being carried out on the NHS in 2009-10. The most common and the most effective procedure is the ‘Roux-en-Y’ gastric bypass, which involves stapling the stomach to create a small pouch at the top, which is then connected directly to the small intestine, bypassing most of the stomach and the duodenum (the first part of the small intestine). This means that patients feel full sooner.

The new study involved data from human trials as well as experiments using rats. The researchers used data from 16 participants in a study in which obese people were randomly assigned either gastric bypass surgery or another type of operation, vertical-banded gastroplasty, in which the stomach volume is reduced but no part of the intestine is bypassed. The participants who had had gastric bypass had a significantly smaller proportion of fat in their diet six years after surgery, based on questionnaire responses.

In the rat experiments, rats given gastric bypass surgery were compared with rats that were given a sham operation. Rats that had gastric bypass surgery ate less food in total, but they specifically ate less high fat food and more low fat food. When given a choice between two bottles with different concentrations of fat emulsions, the rats that had gastric bypass surgery showed a lower preference for high fat concentrations compared with rats that had a sham operation.

“It seems that people who’ve undergone gastric bypass surgery are eating the right food without even trying,” said Mr Torsten Olbers from Imperial College London, who performed the operations on patients in the study at Sahlgrenska University Hospital in Göteborg, Sweden.

Over 7,000 bariatric surgery procedures were carried out in England on the NHS in 2009-10.

Dr Carel le Roux, from the Imperial Weight Centre at Imperial College London, who led the research, said: “It appears that after bypass surgery, patients become hungry for good food and avoid junk food not because they have to, but because they just don’t like it any more. If we can find out why this happens, we might be able to help people to eat more healthily without much effort.”

The rat experiments suggested that the reduced preference for high fat food was partly due to the effects of digesting the food. There was no difference in preferences between gastric bypass rats and sham-operated rats when the rats were only given access to the bottles for a few seconds, suggesting that bypass rats did not dislike the taste of high fat emulsions when they were only allowed small volumes at a time.

Rats can learn to avoid foods that they associate with illness, so the researchers tested whether high fat foods would condition them to avoid certain tastes. They gave the rats saccharine-flavoured water while infusing corn oil into their stomachs. The gastric bypass rats learned to avoid saccharine, but the sham-operated rats did not, suggesting that the effect of digesting corn oil was unpleasant to the rats that had had gastric bypass surgery.

Levels of the satiety-promoting hormones GLP-1 and PYY were higher after feeding in the gastric bypass rats compared with sham-operated rats, suggesting a possible mechanism for the changes in food preferences. The team at Imperial plan to study the role of these hormones further to see if it might be possible to mimic the effects of gastric bypass without using surgery.

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Adjustable Gastric Banding System is a Safe and Effective Weight-Loss Treatment

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Irvine, CA – Two new studies published in the current issue of Surgery for Obesity and Related Diseases, a peer-reviewed journal, add to the large body of scientific evidence which supports that the LAP-BAND® Adjustable Gastric Banding System, made by Allergan, Inc. (NYSE: AGN), is a safe and effective weight-loss procedure. One study concluded that laparoscopic adjustable gastric banding (LAGB) procedure can be safely performed in a community medical practice, with patients experiencing meaningful excess weight loss. The second study examined patients who received LAGB following the failure of gastric bypass and found they achieved significant weight loss two years post-banding procedure.

While a wealth of data has been published in the literature worldwide, questions have recently been raised about the safety and effectiveness of the LAP-BAND® System, specifically with respect to average weight loss and complications. These two new studies support that the advanced product technology of the LAP-BAND® AP System, combined with surgical technique and patient aftercare result in positive clinical outcomes.  The LAP-BAND® System has an 18-year safety and effectiveness record, including almost 10-years in the United States, with more than 650,000 procedures performed worldwide, leading to more than two million patient years of exposure for the device.

- Before and after a Gastric Bypass

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Obese Teens Who Receive Gastric Banding Achieve Significant Weight Loss

Chicago — A higher percentage of severely obese adolescents who received laparoscopic adjustable gastric banding lost more than 50 percent of excess weight and experienced greater benefits to health and quality of life compared to those in an intensive lifestyle management program, according to a study in the February 10 issue of JAMA.

Adolescent obesity is a serious health challenge globally. In the U.S., more than 17.4 percent, or more than 5 million adolescents were obese in 2004, an increase from 14.8 percent in 2000. Obesity is associated with both immediate and late health effects and reduced life expectancy, according to background information in the article. Lifestyle programs that have included changes in diet, exercise, and behavior to promote weight loss often have poor results. “Bariatric surgery is now extensively used for adults and is being evaluated for adolescents,” the authors write. “Laparoscopic adjustable gastric banding (gastric banding) has the potential to provide a safe and effective treatment.”

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Lap band surgery effective for morbidly obese children

In FDA-approved trial, adolescents had 45 percent weight loss two years after surgery

Washington, DC — A surgeon at Children’s National Medical Center and his colleagues from New York University have found laparoscopic adjustable gastric banding (Lap band) to improve the health of morbidly obese adolescents.

The study, published in the Journal of the American College of Surgeons, involved nearly 50 girls and boys ages 14-17. The participants showed significant decreases in total and android fat mass 2 years after surgery. Android fat has been linked to the development of obesity-related illnesses, such as diabetes, heart disease, and insulin resistance.

“This study is the first to demonstrate the improvements in overall health and distribution of weight loss after Lap band surgery in adolescents,” said Evan Nadler, MD, the lead author and pediatric surgeon at Children’s National. “While weight-loss surgery should always be a last resort for adults and adolescents, these findings show us that surgery in adolescents reduces the risk of significant health complications.”

The study found that Lap band surgery improved glucose metabolism, reducing the adolescents’ risk of developing insulin resistance. Additionally, bone mineral density was not impacted by the surgery, suggesting that bone growth is not affected.

Dr. Nadler is the co-director of the Obesity Institute at Children’s National Medical Center, which is comprehensively addressing the epidemic of childhood obesity. Staff includes pediatricians, nutritionists, psychologists, cardiologists, gastroenterologists, and surgeons who treat patients and families in a clinical setting. The Obesity Institute also includes researchers looking at genetic differences and racial disparities, particularly among children and adolescents, as well as community-based research among different ethnic groups.

Dr. Nadler was an investigator for Allergan, which makes the device used in the study. Funding was provided by the Harris Obesity Prevention Effort at New York University and performed at NYU Medical Center.

Source: www.childrensnational.org