Obesity is a serious public health problem associated with increased morbidity and mortality and decreased quality of life. According to the World Health Organization, in 2005 there were about 1.6 billion overweight adults (aged 15 years or older) and at least 400 million obese adults worldwide.1
The prevalence of obesity has increased so rapidly over the last few decades that it is now considered a global epidemic.
The World Health Organization defines overweight as a body mass index (BMI) of 25 or more and obesity as a BMI of 30 or more.1
Obese patients are further categorized into class I (BMI 30–34.9), class II (BMI 35–39.9) and class III (BMI 40 or more).2,3
While these subcategories are relevant when analyzing trends in prevalence, evidence suggests that the risk of chronic disease increases progressively from a BMI as low as 21.1
In addition, the risk of obesity-related comorbidities increases in individuals with a large waist circumference, even if they are categorized as healthy or overweight. Specifically, a waist circumference greater than 101.6 cm (40 inches) in men and greater than 89.9 cm (35 inches) in women predicts an increased risk of diabetes, dyslipidemia, hypertension and cardiovascular disease.
In the United States, the National Health and Nutrition Examination Surveys conducted by the Centers for Disease Control study the prevalence of obesity using directly measured heights and weights. Studies have reported that currently there are 72 million obese adults. Interestingly, while the prevalence in adults aged 20–74 years has more than doubled over the last 4 decades (13.4% in 1960–1962 v. 35.1% in 2005–2006),4
it seems to have reached a plateau in the last 3 years.5–7
However, when comparing the distribution of BMI in 1976–1980 with that in 2005–2006, it appears that the distribution among adults has shifted, reflecting a change in prevalence of superobesity (BMI > 50), which increased from 0.9% in 1960–1962 to 6.2% in 2005–2006.6
In Canada, statistics from 2004 demonstrated that about 23% (5.5 million people) of adults were obese compared with 14% in the late 1970s.2,8
The total direct cost of obesity in Canada has been estimated to be more than $1.8 billion, which corresponded to 2.4% of the total health care expenditures for all diseases in Canada in 1997.9
When the cost of obesity-related comorbidities was taken into account, the 3 largest contributors were hypertension ($656.6 million), type 2 diabetes mellitus (T2DM; $423.2 million) and coronary artery disease ($346.0 million).9
Studies have indicated that obesity is responsible for more than 2.8 million deaths worldwide per year10
owing to an increased prevalence of related comorbidities, including type 2 diabetes, hyperlipidemia, hypertension, obstructive sleep apnea, heart disease, stroke, asthma, back and lower extremity weight-bearing degenerative problems, several forms of cancer and depression.10–12
In addition, obesity is an independent risk factor for death. A study by Fontaine and colleagues13
demonstrated that compared with an individual with a healthy weight, a 25-year-old morbidly obese man has a 22% reduction in life expectancy, representing about 12 years of life lost. A more recent study that examined 10-year mortality in more than 500 000 Americans aged 50–71 years demonstrated that in middle-aged men and women who were nonsmokers and had no pre-existing illnesses, there was a 20%–40% increase in mortality in those who were overweight and a 2- to 3-fold greater risk among those who were obese.14
As evidenced by the existence of countless weight loss programs, most adults attempt to lose weight at some point in their lives.15
However, diet therapy, with and without supports and pharmaceutical agents, is ineffective in the long-term treatment of obesity.3
In 1991, the National Institutes of Health established guidelines for surgical therapy for morbid obesity (BMI ≥ 40 or BMI ≥ 35 in the presence of substantial comorbidities),16,17
and since then the number of bariatric surgical procedures has dramatically increased. About 144 000 obese individuals received surgical treatment in 2004 compared with about 20 000 in 1999.18
The dramatic increase is most likely related to the use of minimally invasive surgical techniques, increased media coverage and increased patient satisfaction. Of the various available weight-loss strategies, bariatric surgery is the only effective long-term weight-loss therapy for obese individuals.19
The present paper reviews the types of bariatric surgical procedures and their impact on diabetes, sleep apnea, dyslipidemia and hypertension; 4 major obesity-related comorbidities.