The fundamental basis for bariatric surgery for the purpose of accomplishing weight loss is the determination that severe obesity is a disease associated with multiple adverse effects on health which can be reversed or improved by successful weight loss in patients who have been unable to sustain weight loss by non-surgical means. An explanation of possible indications for weight loss surgery as well as specific bariatric surgical procedures. Procedures that are less invasive or those that involve less gastrointestinal rearrangement accomplish considerably less weight loss but have substantially lower perioperative and longer-term risk.
The ultimate benefit of weight reduction relates to the reduction of the co-morbidities, quality of life and all-cause mortality. With weight loss being the underlying justification for bariatric surgery in ameliorating CVD risk, current evidence-based research is discussed concerning body fat distribution, dyslipidemia, hypertension, diabetes, inflammation, obstructive sleep apnea and others.
Indications for Bariatric Surgery
The fundamental basis for bariatric surgery for the purpose of accomplishing weight loss is the determination that severe obesity is a disease associated with multiple adverse effects on health which can be reversed or improved by successful weight loss in patients who have been unable to sustain weight loss by non-surgical means. Failure of medical treatment to accomplish sustained weight loss is common among persons with severe obesity. Intense lifestyle intervention can produce averages of approximately 10% at 1 year and maintain weight loss at 5.3% over 8 years. The weight loss accomplished is highly variable but is sufficient to accomplish improvement in medical and comorbidity control4. Pharmacotherapy may enhance short-term as well as longer-term weight loss5. Specific criteria indicated that bariatric surgery is appropriate for all patients with BMI (kg/m2) >40 and for patients with BMI 35-40 with associated comorbid conditions. These criteria have held up over the ensuing 24 years to the present, although specific indications for bariatric/metabolic surgical intervention have been identified for persons with less severe obesity, such as persons with BMI 30-35 with type 2 diabetes. The indications for bariatric surgery are evolving rapidly to consider the presence or absence of comorbid conditions as well as the severity of the obesity, as reflected by BMI6.
Obesity-related comorbidity is defined as conditions either directly caused by overweight/obesity or known to contribute to the presence or severity of the condition. These comorbid conditions are expected to improve or go into remission in the presence of effective and sustained weight loss.
Obesity Comorbid Conditions
– Atherosclerotic CVD, myocardial infarction, stroke
– Congestive heart failure
– Cardiac arrhythmias
– Type 2 Diabetes, prediabetes
– Non-alcoholic Fatty Liver Disease (NAFLD)/Steatohepatitis
– Obstructive Sleep Apnea
– Degenerative Arthritis
– Polycystic Ovarian Syndrome (female)
– Sexual Dysfunction
– Impaired Renal Function
– Stress Urinary Incontinence
Central Nervous System
– Impaired Cognition
– Pseudotumor Cerebri
– Impaired Quality of Life
– Other Psychopathology
Specific Bariatric Surgical Procedures
Surgical procedures in the past have been considered to function as restrictive in which the size of the gastric pouch is greatly reduced, malabsorptive in which malabsorption of nutrients contributes to weight loss, and a combination of restrictive and malabsorptive components. It is now clear that this construct is an oversimplification and, to some extent, inaccurate. There is ample evidence that neural and endocrine signaling pathways affecting eating behaviors, reduction of appetite, satiety, energy intake, and possibly physical activity are all operative to a variable extent.
- Gastric Bypass
Gastric bypass was developed by Mason in the 1970’s in response to unacceptable complication rates that followed ileojejunal intestinal bypass, a procedure which resulted in malabsorption, diminished food intake, and substantial weight loss with its associated benefits but unacceptable complication rates12.
- Sleeve Gastrectomy
In this procedure, approximately 80% of the body of the stomach is resected, creating a tubular stomach based on the lesser curvature of the stomach. No gastrointestinal to small intestine anastomosis is required. Although some restriction on food intake may occur, gastric emptying is accelerated.
- Adjustable Gastric Banding
An adjustable gastric band is placed about the proximal stomach to constrict the size of the gastric pouch and outlet. The rate of gastric emptying can be adjusted by a balloon connected to a subcutaneous port.
- Gastrointestinal Endoscopic Devices
While several endoscopically placed devices or suturing procedures are under development, placement of gastric balloon(s) has recently been approved by the Food and Drug Administration14.
Bariatric Surgery Safety
While the benefits of weight loss among individuals with severe obesity, particularly those with comorbid conditions, are unquestioned, these benefits must be considered in the context of surgical complications. In the past, complications including perioperative mortality were as much as tenfold more frequent than occur at the present time.
In summary, both perioperative and long-term complications occur following all bariatric surgical procedures. Multiple steps have been taken in the recent years to reduce perioperative mortality to the presently reported minimum comparable to other commonly performed surgical procedures. Longer-term complications requiring reoperation or micronutrient deficiencies require careful surveillance and prompt intervention. These complications are generally judged to occur with sufficiently low frequency and severity so as to not constitute a contraindication to the performance of bariatric surgery in general.