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Mental illness does not affect bariatric surgery weight loss results

April 25, 2017
Obesity Society
A new study compares bariatric surgery outcomes according to preoperative mental illness. Results indicates that the state of mental illness does not affect weight loss results.

People with pre-existing mental health conditions had nearly identical results in weight loss after bariatric surgery as compared to those with no known mental health conditions. Published in Obesity, the scientific journal of The Obesity Society (TOS), this is the first large scale study of its kind to examine the relationship of preoperative mental illness to weight loss and health care use after bariatric surgery.

"Many clinicians are hesitant to consider bariatric surgery in the mentally ill population due to the assumption that they will not fare well. This research counters those assumptions, showing no difference, on average, in weight loss in the mentally ill versus non-mentally ill population," said TOS spokesperson Scott Kahan, MD, MPH, FTOS, Director of National Center for Weight and Wellness. "No prior research has evaluated this research question in a large and detailed study group. While all potential surgical patients should receive a thorough evaluation prior to considering surgery, this research suggests that there appears to be no outright reason to deny consideration of bariatric surgery in patients with mental illness who otherwise are good surgical candidates."

Researchers reviewed electronic health record (EHR) data from over 8,000 adults with and without mental illness, from several health care systems across the United States in 2012-2013, to study weight loss and health care use patterns after bariatric surgery including post-surgery emergency department visits and hospitalization days. The study divided patients with mental illness into three groups: (1) mild to moderate depression or anxiety, (2) severe depression or anxiety and (3) bipolar, psychosis or schizophrenia spectrum disorders.

In the study, groups were compared on weight loss by using generalized estimating equations using B-spline bases, and on all-cause emergency department (ED) visits and hospital days using zero-inflated Poisson and negative binomial regression, up to 2 years after surgery. The results concluded that mental illness was not predictive of differential weight loss up to 2 years after bariatric surgery. "Our findings suggest that this powerful weight loss tool can be equally effective for different groups of patients regardless of pre-existing mental health conditions," said Kristina Henderson Lewis, MD, MPH, SM, Assistant Professor, Department of Epidemiology & Prevention Division of Public Health Sciences at Wake Forest Baptist Medical Center.

Dr. Lewis cautioned that the majority of patients in this study came from systems where patients are psychologically screened prior to surgery, supporting the use of such screening to identify clinically-stable patients. Importantly, patients with pre-operative mental illness were observed to have higher use of the emergency department and hospital after bariatric surgery, a finding that may have clinical implications and requires further study.

In an accompanying editorial published in Obesity, James Mitchell, MD, discussed the impact of pre-surgery mental illness on post-surgery weight loss, as well as post-surgery emergency department visits and hospitalization. He pointed out that while more research is needed on this topic, "The most important finding is that those with mental illness, even in its more severe forms, can experience significant weight loss after bariatric procedures that is similar to the weight loss seen in the non-mentally ill patients. The current findings suggest that health care providers need to strongly consider bariatric surgical procedures for their severely obese mentally ill patients who are in a period of relative stability."

Story Source:

Materials provided by Obesity Society. Note: Content may be edited for style and length.

Journal Reference:

  1. James E. Mitchell. Mental illness and bariatric surgery. Obesity, 2017; 25 (5): 819 DOI: 10.1002/oby.21834

Cite This Page:

Obesity Society. "Mental illness does not affect bariatric surgery weight loss results." ScienceDaily. ScienceDaily, 25 April 2017. <>.
Obesity Society. (2017, April 25). Mental illness does not affect bariatric surgery weight loss results. ScienceDaily. Retrieved December 3, 2023 from
Obesity Society. "Mental illness does not affect bariatric surgery weight loss results." ScienceDaily. (accessed December 3, 2023).

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