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Obesity has reached epidemic proportions throughout the United States and the world. In 2003 it was estimated that 66% of American adults were overweight (body mass index [BMI] > 25 kg/m²), 32% were obese (BMI > 30 kg/m²), and 5% were morbidly or severely obese (BMI > 40 kg/m²). These numbers have been increasing throughout the Untied States and more disturbingly the prevalence of severe obesity has been increasing faster than that of obesity. Over the last 20 years the incidence of morbid obesity has doubled and worldwide more than 300 million people are considered obese. Obesity is associated with significant morbidity with diabetes, hypertension, sleep apnea, congestive heart failure, hyperlipidemia, stroke, coronary artery disease, and cancer all more prevalent in obese subjects. Psychological disturbances are also more prevalent in obese patients and contribute to their overall morbidity. This increased morbidity has made obesity the second leading cause of preventable, premature death in the United States after smoking. In 2000 obesity was estimated to contribute to the deaths of 400,000 Americans. The pathophysiology of obesity is complex and not merely a problem with too much calorie consumption. Genetic, behavioral, psychological, physical, and other factors all play into each individual patient’s weight gain. The low cost availability of good tasting, calorie dense foods has also promoted the development of obesity among the poor. Although genetic factors may play a significant role in obesity, changes in our environment and its interaction with our genetic tendencies have clearly driven the current epidemic.

Bariatric surgery was first performed in the 1950s with the first intestinal bypass. Over the last 50 years there have been a variety of procedures performed for obesity, many with waxing and waning interest. Many physicians still feel that bariatric surgery is experimental and high-risk despite numerous studies to the contrary. These physicians cite the numerous metabolic and nutritional complications of the jejunoileal bypass and the frequent failures of the horizontal gastroplasty as evidence of the failure of bariatric surgery. Bariatric operations performed today, however, are generally safe and effective at achieving and maintaining meaningful weight loss, improving quality of life, and decreasing morbidity and mortality. In 1991 the National Institutes of Health (NIH) Consensus Conference concluded that bariatric surgery was an effective long-term treatment for morbid obesity. At that time the 2 procedures recommended by the Consensus Conference were the vertical banded gastroplasty (VBG) and the Roux-Y gastric bypass (RYGB). Since the NIH Consensus Conference there has been an exponential growth in bariatric operations performed throughout the United States. This growth is likely multifactorial, but important reasons include increased awareness of both primary care physicians and patients of the effectiveness of surgical weight loss and the dissemination of laparoscopic techniques to bariatric surgery.

Since the NIH Consensus Conference there have been dramatic changes in the types of bariatric procedures offered to patients. The VBG is now only rarely performed, with only a few proponents of the technique. Long-term studies have demonstrated inferior weight loss with VBG with no significant difference in complications relative to the RYGB. Some supporters of the VBG have continued to perform the procedure and have adapted laparoscopic techniques to minimize some of the long-term complications. RYGB has now come to be considered by many bariatric surgeons the “gold standard” to which all bariatric operations must be compared. Wittgrove and Clark were the first to describe their technique of laparoscopic RYGB (LRYGB) in 1994. It was not until the late 1990s that LRYGB obtained widespread attention. Since that time there has been considerable experience with the LRYGB and studies have shown that the procedure results in equivalent weight loss and resolution of comorbidities to the open procedure. Although studies comparing postoperative complications between the open and laparoscopic procedure have given mixed results, the greatest advantage of LRYGB over RYGB is in short- and long-term wound complications. Alternatively, in some studies, LRYGB is associated with a higher incidence of postoperative bowel obstruction. The learning curve for LRYGB is long and steep and many studies reporting significant adverse events for LRYGB are typically from a group’s early experience. Mature LRYGB programs have reported postoperative results that are favorable compared with the open procedure.

Although LRYGB has become the new gold standard in the United States, laparoscopic adjustable gastric banding (LAGB) is the most common bariatric operation performed in the rest of the world. The LAGB has replaced the VBG as the purely restrictive operation of choice for many surgeons who do not like the higher perioperative risk profile of the LRYGB. Although LRYGB requires a long and steep learning curve, LAGB is technically easier. The true art of LAGB is the postoperative management of the patients to maximize outcomes. The procedure can be performed as an outpatient and patients can resume normal activities within a short time frame. Frequent follow-up is necessary to ensure adequate weight loss. Although many of the serious complications associated with LRYGB are centered around the immediate postoperative period, LAGB carries with it more long-term complications, albeit the majority of which are minor. Most American and some European trials of LAGB have shown poorer weight loss outcomes than for RYGB. Australian and some European studies would suggest that the LAGB can result in weight loss similar to that seen in large cohorts with the RYGB with a more favorable safety profile. The only randomized controlled trial concluded that the weight loss of LAGB was less than LRYGB and the failure rate was higher with LAGB. Larger studies will be required to further validate these findings.

Biliopancreatic diversion (BPD) was first described by Nicola Scopinaro and has been an excellent weight loss operation for severely morbidly obese patients. Weight loss is typically 70% to 80% of excess body weight and is maintained for up to 20 years. The procedure is complex and the patients can be challenging to take care of in the long term due to the nutritional and metabolic side effects of the operation. Some surgeons have modified the BPD to decrease the degree of malabsorption and alter the gastrectomy to preserve the pylorus and proximal duodenum in a construction called the duodenal switch (BPD-DS). They have reported improvements in the rates of ulcer and nutritional deficiencies relative to the BPD. Both procedures are being performed laparoscopically, but excellent laparoscopic skills are necessary to undertake either of these procedures.

Weight loss with bariatric surgery is dramatically better than can be achieved with medical means. The gastric bypass results in average excess weight loss of 70% at 1 year, whereas LAGB is slightly lower and BPD-DS slightly higher than that figure. All operations tend to be associated with a regain of a small proportion of lost weight in the 5 years after operation. Although many patients that present for bariatric surgery focus on the amount of weight loss, the true benefit of weight loss surgery is the reduction in obesity-related comorbidities and the subsequent prolongation of life. Weight loss surgery, regardless of the procedure, improves many patient comorbidities including diabetes, hypertension, hyperlipidemia, sleep apnea syndrome, nonalcoholic fatty liver disease, and gastroesophageal reflux disease. Many of these comorbidities improve fairly quickly after operation, with occasional patients stopping medications before discharge from the hospital. Although many patients report a significant improvement in overall quality of life after bariatric surgery, improvements in depression are not always long lasting. Recent studies have shown a long-term mortality reduction in surgical cohorts compared with similar groups of obese patients who do not undergo bariatric surgery. The Swedish Obese Subjects trial is an ongoing prospective matched cohort study examining weight loss, major morbidity, and mortality in obese subjects after bariatric surgery compared with similar patients who do not have surgery. This study has shed much light on the long-term benefits of bariatric surgery.

The postoperative complications after any bariatric operation can be divided into early, intermediate, and late, with some overlap between them. Early complications of all bariatric procedures include bleeding, deep venous thrombosis, myocardial infarction, pulmonary dysfunction, and wound infection. In patients undergoing procedures involving rerouting of the alimentary stream, there are unique risks including anastomotic leaks and bowel obstruction through a mesenteric defect that can be catastrophic if the blood supply to the bowel is compromised. Patients undergoing restrictive operations have the potential to develop outlet obstruction. Stomal stenosis between 30 and 60 days after gastric bypass is not uncommon and can be treated with endoscopic dilation, but stomal stenosis several years after a restrictive procedure may not respond as well. Acute obstruction and band slippage after LAGB results in complete gastric obstruction that usually requires operative correction. Anastomotic ulcers also present a challenge but can usually be managed medically. Nutritional complications are particularly common after malabsorptive procedures and patients should be followed for the long term since these complications often do not occur for several years after operation. Among the most common long-term complications is suboptimal weight loss or weight regain.

The morbidly obese patient does not respond to intra-abdominal complications in the same way as the nonobese patient. Although each of the previously mentioned complications has “classic” manifestations, they are not always present in the morbidly obese patient. Therefore, a high index of suspicion for a complication is warranted for any bariatric patient who does not progress down the regular postoperative pathway. Tachycardia, fever, and dyspnea are harbingers of potential abdominal catastrophes in the bariatric patient and demand prompt attention.

Bariatric surgery, like the rest of general surgery, is constantly evolving. Future treatments in bariatric surgery aim to improve on weight loss as well as complication rates for existing bariatric procedures. Another important area of future research is to examine the relationship between weight loss and the degree of morbidity and mortality benefit. Innovative procedures are on the horizon that may trade off weight loss effectiveness for a more favorable procedural risk profile. Sleeve gastrectomy has gained a lot of attention recently as a definitive weight loss operation. It has been noted that the short-term results for patients who have undergone sleeve gastrectomy as part of a 2-stage procedure are excellent. Long-term results for this technique are currently lacking and many surgeons are calling for prospective studies to determine the efficacy of the procedure. The endoluminal treatment of morbid obesity has also gained significant interest. The potential to produce significant weight loss with no incision and minimal morbidity and mortality is the promise of many of these procedures. Endoluminal balloons and stapling devices are the current techniques under investigation. Several small human studies have shown some promise with very short-term follow-up. Finally, electrical stimulation of the stomach and the vagus nerves has been in evolution for the last decade. Several studies have shown mixed results with different types of stimulators and different modes of stimulation. There are multiple studies currently being performed in different stages of development.

Bariatric surgery has undergone many changes since the first procedures were performed in the 1950s. Many physicians and surgeons remain ignorant of these changes, but they will not be able to remain so much longer. With the increase in obesity and even more recent dramatic increase in bariatric procedures, these physicians and surgeons will find themselves managing these patients at some point in their career.