When Bariatric Surgery Comes Up Short: Probing the Behavioral-Biological Reasons

Bariatric surgery is the most efficacious and durable intervention for severe obesity — except when it isn’t.

Despite established weight-loss and health benefits for many of the nearly 200,000 Americans who undergo bariatric surgery each year, a subset of these patients experience suboptimal weight loss or substantial weight regain after initial success. Now a team of investigators at seven U.S. institutions is aiming to better understand why, with help from a $4.5 million, five-year grant award from the National Institute of Diabetes and Digestive and Kidney Diseases.

The grant is funding a prospective, longitudinal study examining how biological and behavioral mechanisms interact to determine the success of bariatric surgery.

“The etiologic contributors to weight loss success following bariatric surgery are not well understood,” explains the study’s co-principal investigator (PI), Leslie Heinberg, PhD, Section Head of Adult Psychology in Cleveland Clinic’s Department of Psychiatry and Psychology and Center for Behavioral Health. “Weight change likely involves complex interactions between behavioral and biological factors, and it’s difficult to predict which bariatric surgery patients may experience suboptimal outcomes.”

The study in brief

She and her co-investigators will examine interrelationships among factors ranging from eating disorders to the gut’s bacterial composition to physical activity, mood symptoms and cognitive function. “The longitudinal relationship between changes in the gut microbiome and postsurgical weight trajectory has not been explored thoroughly,” notes Dr. Heinberg, who is also Director of Behavioral Services for Cleveland Clinic’s Bariatric and Metabolic Institute. “And any associations between the microbiome and other variables that impact weight have been similarly understudied.”

To fill those knowledge gaps, the multicenter investigation will prospectively study 144 patients undergoing two of the most common bariatric procedures — Roux-en-Y gastric bypass and sleeve gastrectomy — and monitor them over 24 months following surgery to assess for correlates and predictors of observed weight loss trajectories.

Enrollment is underway, but because of the longitudinal nature of the study, results won’t be known for at least two years.

The aim is to generate data to allow physicians to better identify bariatric surgery candidates who are more likely to have suboptimal outcomes — and perhaps help target modifiable risk factors through interventions. “We hope our findings may enable a shift toward more individualized medicine in the care of patients with obesity who are considering bariatric surgery,” Dr. Heinberg says.

She is joined in this effort by co-PI Kristine Steffen, PharmD, PhD, of North Dakota State University, and researchers from diverse disciplines and centers across the U.S.

Comprehensiveness of care is key

This study is the latest in a series of NIH-funded research projects on obesity in which Dr. Heinberg has served as a principal investigator, co-investigator or consultant from a behavioral health perspective. Along with obesity and bariatric surgery, her specialty interests include eating disorders and disorders of body image.

“Severe obesity is a complex, chronic disease that requires multidisciplinary care,” she says, noting that this is one of many collaborative research projects within Cleveland Clinic’s Bariatric and Metabolic Institute, where she works with surgeons, physicians, psychologists, dietitians and nurses who provide comprehensive care to patients with clinical obesity. “This research will help illuminate how to optimize outcomes for patients wishing to lose weight and maintain their weight loss.”