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Am Fam Physician. 2022;105(6):593-601

Related Letter to the Editor: Alcohol Use Disorder Following Metabolic Surgery

This clinical content conforms to AAFP criteria for CME.

Author disclosure: A public database shows that Dr. Harrison has attended an industry-sponsored training course for robotic-assisted surgery; this is considered standard practice and is required to use the surgical platform in bariatric surgery. He has not served as a speaker or consultant for this company. Drs. Banerjee and Schroeder have no relevant financial relationships.

In 2019, approximately 256,000 metabolic surgery procedures were performed in the United States, a 32% increase since 2014. The most common procedures are the laparoscopic sleeve gastrectomy and the Roux-en-Y gastric bypass. Choice of procedure depends on concurrent medical conditions, patient preference, and expertise of the surgeon. These procedures have a mortality risk of 0.2% to 0.3%. On average, weight loss of 30 to 50 kg (66 to 110 lb), or a 20% to 30% reduction in total body weight, is achieved, although most patients will experience some weight regain three to 10 years after surgery. In patients who have had metabolic surgery, all-cause mortality is reduced by 30% to 45% at two to 15 years postsurgery compared with patients with obesity who did not have surgery. Approximately 70% of surgical patients achieve remission of type 2 diabetes, and over 30% of surgical patients maintain remission at 10 years. [corrected] Other obesity-related conditions are also greatly reduced, and quality of life improves. Postoperatively, patients require standardized nutritional supplementation and surveillance. Persistent changes in diet, such as consuming protein first at every meal, regular physical activity, and ongoing attention to behavior change are critical for the success of the patient after metabolic surgery. Common adverse outcomes include surgical complications, nutritional deficiencies, bone density loss, dumping syndrome, gastroesophageal reflux disease, and loose skin. The family physician is well positioned to counsel patients about metabolic surgical options and the risks and benefits of surgery and to provide long-term support and medical management for postsurgery patients.

Obesity is a disease that has serious physical, psychological, and economic implications for patients and the health care system.1 When defined by a body mass index (BMI) of 30 kg per m2 and above, 42% of the current U.S. adult population have obesity, and 9% have class 3 obesity (BMI greater than or equal to 40 kg per m2).2 The primary care office can be a supportive, nonjudgmental environment for patients with obesity by connecting them with evidence-based treatment resources. The Strategies to Overcome & Prevent (STOP) Obesity Alliance ( provides resources for physicians,3 and the Obesity Action Coalition ( provides resources for patients and physicians.4
On average, patients who have metabolic surgery lose 26 kg (57 lb) more than those with nonsurgical weight loss and are five times more likely to experience remission of diabetes mellitus.5 According to the American Society for Metabolic and Bariatric Surgery, approximately 256,000 metabolic surgeries were performed in the United States in 2019, a 32% increase in five years.6 The term metabolic surgery is now preferred because of the metabolic effects of surgical procedures beyond weight loss.7

What Procedures Are Commonly Performed?

As of 2019, laparoscopic sleeve gastrectomy (60%) and Roux-en-Y gastric bypass (18%) were the most common metabolic surgeries.6 The choice of procedure depends on patient preference, the expertise of the surgeon and surgical center, and risk stratification.7


The sleeve gastrectomy procedure resects most of the body and all of the fundus of the stomach, creating a long, narrow, tubular stomach (Figure 18). Single anastomosis duodenal-ileal bypass with sleeve was endorsed by the American Society for Metabolic and Bariatric Surgery in 2020 and will likely become more prevalent in the coming years.9 Single anastomosis duodenal-ileal bypass with sleeve adds a bypass of the duodenum to traditional sleeve, which can be performed as a single procedure or as a revision to a prior sleeve gastrectomy (Figure 2).

In Roux-en-Y gastric bypass, a small gastric pouch is formed by dividing the upper stomach and joining it with the resected end of the jejunum so that food bypasses the stomach and upper small bowel, thereby restricting the size of the stomach and causing some malabsorption (Figure 38).

Family physicians may see patients who have a laparoscopic adjustable gastric band (Figure 48). The adjustable gastric band now accounts for less than 1% of procedures because of a higher complication rate and lesser weight loss.6,10

How Does Metabolic Surgery Lead to Weight Loss and Improvement in Type 2 Diabetes?

Weight loss and improvement in type 2 diabetes result from complicated neuroendocrine changes that lead to decreased hunger, increased satiety, and improved glycemic control combined with a physically smaller stomach.11


Procedures were previously conceptualized as restrictive (create a smaller stomach), malabsorptive (bypass normal anatomy), or a combination, resulting in a calorie deficit. However, improvements in blood glucose levels and other obesity-related conditions occur earlier than can be fully explained by weight loss. Research indicates that the mechanisms of action include multiple physiologic variables that impact a complex neuroendocrine system involving the gut, central and peripheral nervous systems, and adipocytes to regulate energy homeostasis.11 Glucagon-like peptide-1 and peptide YY increase after Roux-en-Y gastric bypass and sleeve gastrectomy.11 Glucagon-like peptide-1 enhances insulin secretion, whereas peptide YY increases satiety and delays gastric emptying. Other hormones affected by metabolic surgery include insulin, ghrelin, leptin, C-reactive protein, interleukin-6, tumor necrosis factor–alpha, and adiponectin.11,12
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