Bariatric Surgery & Disordered Eating

Bariatric surgery is a category of procedures performed on the stomach or intestines to induce weight loss. Though bariatric surgery is gaining in popularity, the decision to pursue it is best made with a sense of what is and isn’t known about it.

Bariatric surgery is the most effective long-term treatment for severe obesity currently available. Though there are some distinctions by country and region, the most commonly performed bariatric procedures worldwide are:

  • Gastric bypass (45%)
  • Vertical sleeve gastrectomy (37%)
  • Adjustable gastric banding (10%)

How the Surgeries Work

Gastric bypass and vertical sleeve gastrectomy involve a permanent, irreversible change to anatomy. Vertical sleeve gastrectomy and adjustable gastric banding reduce the size of the stomach to restrict food intake and promote an earlier sense of fullness; gastric bypass surgery additionally alters the path of food through the gastrointestinal tract such that the body reduces its absorption of calories and various nutrients. The mechanisms by which these procedures produce their results, however, are likely even more complicated than originally thought. Studies show that people can experience post-operative changes in food preferences, intolerances, tastes, and food-related rewards, as well as changes in energy expenditure and signaling to and from the brain.

Psychological Wellbeing Prior to Surgery

Anyone considering bariatric surgery must complete a pre-operative psychological evaluation to determine if there is a mental health problem that might interfere with sticking to the many nutritional and physical health recommendations made by the surgical and post-operative treatment team.

Unmanaged psychiatric problems such as suicidality, untreated mood disorders, and substance use disorders are contraindications for surgery.

Eating disorders characterized by self-induced vomiting are also a contraindication for surgery. As we have described elsewhere, purging behaviors are dangerous and medically compromise anyone seeking to undergo a major operation. Because these particular procedures all involve stomach repair, vomiting can result in dangerous post-operative complications.

To be as successful with any of these procedures as possible, consistency with lifestyle change factors – increasing physical activity and reducing intake – is key. The diet mindset characteristic of many eating disorders, if unaddressed, may make adherence to the post-operative nutritional plan problematic.

Disordered Eating Behaviors after Surgery

A review of bariatric surgery studies found that gastric bypass is associated with reductions in binge eating disorder and related symptoms in the short- and medium-term, but that there is a risk of a subsequent increase in symptoms. Gastric bypass has been shown to reduce emotional eating in the short- to medium-term.

Not surprisingly, there is strong evidence – across procedures – that the presence of post-surgical binge eating disorder or binge eating episodes is associated with poorer weight loss or greater weight regain. Eating disordered attitudes (for example, high levels of body shape or weight concern) following surgery are negatively associated with outcome. Even post-operative loss of control eating episodes, in which a person eats a usual or small amount of food but feels out of control while eating, seem to negatively impact weight outcome. Night eating syndrome, one of the Other Specified Feeding and Eating Disorders (OSFED) described in the DSM-5, is experienced pre-surgery by up to 20% of those pursuing a bariatric procedure. While symptoms appear to decrease after weight loss surgery, some, but not all, studies indicate that post-operative night eating syndrome may also be associated with less weight loss.

Taken together, these findings suggest that post-operative specialized care for individuals vulnerable to eating disorders ought to be an important part of the treatment plan.

Other Psychological Changes Post-Op

In general, research has shown that in the period after bariatric surgery people report improvements in their quality of life, self-esteem, and mood. It is less clear what happens in the long term. However, as more people undergo these procedures as more time passes after surgery, there are more data to mine for information on outcomes that can help inform follow-up care.

A recently discovered trend, for example, is a notable change in alcohol use patterns in individuals following bariatric surgery. One study found that the prevalence of regular drinking doubled in the five years following gastric bypass and adjustable gastric banding, with the prevalence of an alcohol use disorder increasing over time as well. There are several hypotheses as to why this might be. It may be that people have a different experience of drinking alcohol post-surgery due to greater effects of the same amount of alcohol consumed. Or, people may become more social after surgery and therefore have more occasions to drink while socializing with friends and loved ones. Regardless of the “why,” the “what” is clear – information about the increased risk for an alcohol use disorder can be used to educate people about what to watch out for prior to surgery and inform post-operative clinical assessment by the treatment team.


Bariatric surgery “fixes” the GI tract, but not the brain. A difficulty with binge eating can recur after surgery for some people. For those who are severely obese, these procedures can significantly improve medical status and quality of life. As with all surgeries, bariatric surgery is not without risks. Outcomes are variable and highly dependent on an individual’s ability to stick to lifestyle changes.

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