Depression and anxiety are common among morbidly obese patients who have weight loss surgery. In a 2011 study, Jonathan Finks, an assistant professor of surgery of University Michigan and his co-authors observed that 46% of the patients receiving weight loss surgery had a psychiatric disorder.
They examined data from the Michigan Bariatric Surgery Collaborative that contains data of more than 26,000 patients who have undergone weight loss surgery since 2006. The surgeries included gastric bypass, gastric sleeve, gastric banding, and the duodenal switch (similar to gastric bypass, but keeps some stomach and passes most of the intestine).
Before the surgery, 72% of patients with depression used antidepressants. A year after bariatric surgery, the percentage of people taking antidepressants dropped to 60%. Finks added that the percentage of people responding to the surveys a year later dropped to just 31%.
While weight loss alone can’t cure clinical depression, most post-surgical patients do report a significant improvement in their mood and outlook on life.