News Release

Study: Gastric bypass surgery associated with non-alcohol substance use disorder

Peer-Reviewed Publication

The Obesity Society

ROCKVILLE, Md.—Researchers have discovered a link between gastric bypass surgery and an increased risk of non-alcohol substance use disorder, according to a new study in Obesity, The Obesity Society’s (TOS) flagship journal.

“The current study shows that non-alcohol substance use disorder was 2.5 times more common after gastric bypass surgery compared with controls receiving usual obesity care, but the total number of patients having non-alcohol substance use disorder was overall low. Healthcare professionals should consider the risk of non-alcohol substance use disorder in the care of patients treated with gastric bypass surgery,” said Professor Per-Arne Svensson, PhD, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden and the Institute of Health and Care Sciences, Sahlgrenska Academy, University of Gothenburg. Svensson is the corresponding author of the study.

Experts note that one previously acknowledged side effect of bariatric surgery is an increased intoxication level after alcohol consumption. It’s also been reported that gastric bypass surgery is associated with an increased incidence of alcohol abuse. In recent years, however, studies have shown substances other than alcohol have been over consumed after bariatric surgery.

In the current research, Swedish Obese Subjects (SOS) study, enrolled 2,010 patients with obesity who underwent bariatric surgery – 265 patients for gastric bypass, 1,369 with vertical banded gastroplasty and 376 patients with gastric banding. A total of 2,037 matched control individuals received usual obesity care. Participants who had non-alcohol substance use disorders were identified using the International Statistical Classification of Diseases (ICD) from the Swedish National Patient Register (NPR) covering hospital treatment but not primary care.

The study was conducted at 25 public surgical departments and 480 primary health centers throughout Sweden. Participants were between the ages of 37 and 60, and had a body mass index (BMI) of at least 34 kg/m2 for males and 38 kg/m2 for females. The study included patients from September 1987 to January 2001 with a follow up period of nearly 24 years.

Results revealed that only gastric bypass surgery was associated with increased incidence of non-alcohol substance use disorder compared with control participants. The most common diagnoses were other psychoactive substance-related disorders; sedative, hypnotic or anxiolytic related disorders and opioid related disorders.

In addition, when the groups that had undergone different surgical procedures were compared with each other, no statistical difference in incidence of non-alcohol substance use disorder was detected.

“It is important to acknowledge that the number of affected patients was relatively low, in the single digits,” said Jihad Kudsi, MD, MBA, MSF, DABOM, FACS, FASMBS, a bariatric surgeon and chairman of surgery, Duly Health and Care, Oak Brook, Ill. Kudsi was not associated with the research.

Kudsi added, “These significant findings further reinforce the recommendations of the American Society for Metabolic and Bariatric Surgery and highlight the critical role of bariatric behavioral health clinicians in the comprehensive evaluation and care of patients both before and after weight-loss surgery. It is noteworthy that a history of past substance abuse or dependence, which has fully remitted, should not be considered a contraindication for weight-loss surgery.”

The study’s authors noted that further research to address this risk is warranted.

Other authors of the study include Johanna C. Andersson-Assarsson, Sofie Ahlin, Peter Jacobson, Magdalena Taube, Kajsa Sjöholm and Lena M.S. Carlsson, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden. Ahlin is also with the Region of Västra Götaland, NU Hospital Group, Department of Clinical Physiology, Trollhättan, Sweden. Petra Brembeck and My Engström, Institute of Health and Care Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden, also served as co-authors. Engström is also with the Department of Surgery, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden. Markku Peltonen, Chronic Disease Prevention Unit, National Institute for Health and Welfare, Helsinki, Finland, also co-authored the study.

The authors declared no conflict of interest.

The study, titled “Non-Alcohol Substance Use Disorder After Bariatric Surgery in the Prospective,  Controlled Swedish Obese Subjects Study,” is online and will be published in the print issue of Obesity in August 2023.

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The Obesity Society (TOS) is the leading organization of scientists and health professionals devoted to understanding and reversing the epidemic of obesity and its adverse health, economic and societal effects. Combining the perspective of researchers, clinicians, policymakers and patients, TOS promotes innovative research, education and evidence-based clinical care to improve the health and well-being of all people with obesity. For more information, visit

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