Obesity has become a global problem. The definition and classification of obesity is based on the body mass index (BMI), which is calculated as weight in kilograms divided by height in meters squared. An estimated 1.7 billion adults worldwide are now considered overweight (BMI > 25 kg/m2). Of these, 300 million are obese (BMI > 30 kg/m2). In the United States, two-thirds of adults are overweight, one-third of adults are considered obese, and almost 5% are morbidly obese (BMI > 40 kg/m2). In addition, the number of obese children has more than doubled over the past 3 decades to 16%. The more than 50 million obese Americans are at risk of developing numerous obesity-related health problems, including hypertension, diabetes, and coronary artery disease, to name just a few (Table 68-1).
Table 68-1 Obesity-Related Comorbidities ||Download (.pdf)
Table 68-1 Obesity-Related Comorbidities
- Type 2 diabetes
- Coronary artery disease
- Obstructive sleep apnea
- Obesity hypoventilation syndrome
- Gastroesophageal reflux disease (GERD)
- Pseudotumor cerebri
- Sex hormone anomalies
- Polycystic ovary disease
- Stress urinary incontinence
- Venous stasis disease
- Deep venous thrombosis
- Degenerative joint disease
- Abdominal wall hernias
Currently, the annual cost for treating obesity and its related comorbid conditions is estimated at $100 billion. Obesity accounts for more than 100,000 premature deaths annually and is considered the second most preventable cause of death, after cigarette smoking.
To date, surgery is the most effective means of achieving and maintaining long-term weight loss in obese patients. Weight loss, measured as percentage of excess body weight loss (EBWL is calculated as weight loss/excess weight × 100), and improvement in comorbid conditions varies with the different types of procedures. Maximum weight loss is most often seen in the first 1 to 2 years after surgery.
The Roux-en-Y gastric bypass (RYGB) is currently the most common bariatric procedure performed worldwide. Much of the popularity stems from the ability to perform the surgery laparoscopically and the significant weight loss that can be achieved by the patients. The Swedish Obese Subjects Study, the largest study on weight loss surgery to date and the study with the longest follow-up, reports a mean percent weight loss of 32.5% of total body weight (percent of total weight loss is roughly equal to half of EBWL) 1 to 2 years after gastric bypass and 25% 10 years post-bypass. A 2004 meta-analysis by Buchwald et al, reported a mean EBWL of 61.6% after 1 to 2 years, which is comparable to the Swedish Obese Subjects Study.
Roux-en-Y gastric bypass also provides excellent improvement and even remission of comorbid conditions (Table 68-2).
Table 68-2 Outcomes of Various Bariatric Surgeries