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DANVILLE, Pa. -- A Geisinger Health System study of patients who underwent gastric bypass surgery found that those who used insulin prior to surgery, had a history of smoking, or took 12 or more medications maintained the greatest weight loss 7 to 12 years after the surgery. The study was published online Wednesday by JAMA Surgery.

Michelle R. Lent (right), Ph.D., a Geisinger Obesity Institute researcher, and her team examined the electronic health records of 726 patients for preoperative conditions and factors – including medications, chronic diseases, lab results and demographics – and determined percentage weight loss following the surgery. Patients in the study averaged a 22.5 percent weight loss 7 to 12 years after surgery.

“While bariatric surgery is the most effective long term treatment for obesity, some patients do better than others when it comes to weight loss,” Dr. Lent explained. “If we can identify those patients who may be at risk for losing less weight, we can tailor their treatment to help them lose as much weight as possible.”

The study is the first to find that patients with diabetes and using insulin demonstrated the greatest long-term weight loss after gastric bypass surgery. Those patients lost seven percent more weight than the average.

“Patients using insulin ended up being the slow, steady weight loss winners, which we did not expect,” Lent said. “We theorize that may be because these patients are typically advised to watch their diets closely to manage their diabetes. Perhaps the dietary recommendations associated with insulin use help them lose more weight when compared with other patients.”

Patients with a history of smoking or those who took 12 or more medications lost 3 percent more weight.

Smoking was a surprise since it is generally associated with worsening health outcomes. But Lent says because those patients had to quit smoking in order to have the surgery, they may have already demonstrated a history of changing their behavior to improve upon their health and are therefore also able to change their eating behaviors.

Those on the most medications also may have had the most to gain from the weight loss surgery.

“They could possibly be sicker, so they may be the most motivated to change their behavior,” Lent said. “Or, those who are taking that many medications may already have more touch points within the health system, so they may be seeing doctors more frequently.”

Older patients (55 and older) lost nearly 9 percent less weight than the average. Patients with higher body mass indexes (BMI) also lost 4 percent less weight, while those with preoperative high cholesterol lost 3 percent less.

Geisinger Health System is an integrated health services organization widely recognized for its innovative use of the electronic health record and the development of innovative care delivery models such as ProvenHealth Navigator® and ProvenCare®. As one of the nation’s largest health service organizations, Geisinger serves more than 3 million residents throughout 45 counties in central, south-central and northeast Pennsylvania, and also in southern New Jersey with the addition of AtlantiCare, a National Malcolm Baldrige Award recipient. The physician-led system is comprised of approximately 30,000 employees, including nearly 1,600 employed physicians, 12 hospital campuses, two research centers and a 510,000-member health plan, all of which leverage an estimated $8.9 billion positive impact on the Pennsylvania economy. Geisinger has repeatedly garnered national accolades for integration, quality and service. In addition to fulfilling its patient care mission, Geisinger has a long-standing commitment to medical education, research and community service. For more information, visit, or follow the latest Geisinger news and more on Twitter and Facebook.


CONTACT: Mike Ferlazzo, 570-214-7410,