Newswise — Some patients who undergo weight loss surgery to combat obesity don’t lose the pounds they expect or they gain weight back. A team of researchers at seven institutions across the United States is working to find out why.

Kristine Steffen, PharmD., Ph.D., in North Dakota State University’s College of Health Professions, is receiving a $3.7 million, five-year grant award for a study that examines how biological and behavioral factors interact in determining the success of bariatric surgery.

As associate professor of pharmaceutical sciences in the NDSU School of Pharmacy, Steffen serves as co-principal investigator in the study. The grant award from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health supports Steffen’s research. According to the American Society for Metabolic and Bariatric Surgery, an estimated 196,000 bariatric surgeries were conducted in 2015.

“There is a subset of patients who experience sub-optimal weight loss or weight re-gain following surgery. The factors that determine weight loss outcomes following surgery are still poorly understood,” said Steffen. “The goal of this project is to identify key behavioral and biological changes that predict post-surgical weight outcomes.”

The research team will investigate factors for each of the two most common bariatric surgery procedures—Roux-en-Y Gastric Bypass and Sleeve Gastrectomy. According to Steffen, data from the study may allow doctors to better identify bariatric surgery candidates who are at risk for sub-optimal outcomes after surgery. Information from the study also may help clinicians target risk factors that can be modified.

The research team will investigate the inter-relationships between the bacterial composition of the gut and problematic eating behaviors, physical activity, mood symptoms, and cognitive function.

“Data and analysis from the study will be instrumental in moving toward individualized medicine in caring for patients with obesity who seek bariatric surgery,” said Steffen.

The research team includes: co-principal investigator Dr. Leslie Heinberg, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University; Drs. Ross Crosby, James Mitchell and Molly Orcutt, Neuropsychiatric Research Institute, Fargo; Dr. Luis Garcia, Sanford Eating Disorders and Weight Management Center; Drs. Ian Carroll and Christine Peat, University of North Carolina at Chapel Hill; Dr. John Gunstad, Kent State University; and Dr. Dale Bond, Brown University.

Statistics from the Centers for Disease Control and Prevention estimate that 44 percent of the U.S. population will be considered obese by 2030. The percentage of adults age 20 and over considered to be obese was nearly 40 percent of the population in 2013-14, according to the CDC, which also maps the prevalence of obesity across the country.

The research titled “Mechanisms that Predict Weight Trajectory after Bariatric Surgery: The Interactive Roles of Behavior and Biology” is supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number R01DK112585. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

About NDSUAs a student-focused, land grant, research institution, NDSU serves the citizens of North Dakota. NDSU is listed in the top 100 research universities in the U.S. for R&D in agricultural sciences, chemistry, computer science, physical sciences, psychology, and social sciences, based on research expenditures reported to the National Science Foundation. Researchers in the College of Health Professions at NDSU conduct research in nursing, public health, pharmacy practice and pharmaceutical sciences, covering a wide variety of topics.