The aim of this article is to describe the context in which this issue of Gastrointestinal Endoscopy Clinics of North America is established. The authors review the current worldwide dimensions and trends of the obesity epidemic; associated mortality and comorbid diseases including diabetes, cancer, cardiovascular disease and obstructive sleep apnea; the financial impact of obesity; and current national and international guidelines for referral and qualification for surgical treatment of obesity.
The aim of this article is to describe the context in which this issue of Gastrointestinal Endoscopy Clinics of North America is established. The authors review the dimensions of the obesity epidemic, associated comorbid diseases, the impact of obesity, as well as current national and international guidelines for referral and qualification for surgical treatment of obesity.
Definitions
Many classifications have been used to measure and define obesity, and specifically to quantify the relationship between obesity and its impact on overall health and on the incidence of comorbidities and mortality.
The measurements used include waist circumference, total body fat, percent body fat, body mass index (BMI), and skin fold thickness. No single parameter has yet been able to adequately correlate obesity and its related comorbidities and to provide the optimal screening tool. However, waist circumference (reflecting central obesity) has been described as potentially carrying the strongest association with cardiovascular disease risk factors when compared with other measures of adiposity. Consequently, a threshold of 40 in (101.5 cm) in males and 35 in (89 cm) in females has been set for an increased risk of cardiovascular disease and other comorbidities. This threshold puts most patients with a BMI greater than 35 in an increased risk category, without further differentiation. This delineation is therefore currently more limited to the “leanest” of the obese patients, and its discriminating superiority over BMI is not clearly established.
BMI remains the most widely used classification of obesity. It has been demonstrated to be a strong predictor of overall mortality as well as to be directly associated with the presence of comorbidities. Although BMI does not distinguish fat and lean body mass, it carries the advantage of being widely used, intuitive, and totally reproducible without operator-dependent or technique-dependent variations (such as skin fold thickness). BMI also integrates undernutrition in the same measurement scale, with a good association with increased mortality in this population. BMI is therefore the most commonly used screening tool in quantifying obesity and is used in most international guidelines.
The question of weight standards also remains imperfectly defined. In the past, the ideal weight range for an individual was determined according to standard tables published by insurance companies. These tables were based on the average weight and height of their customers, and a 20% margin was accepted above and below the average. The most famous of these tables were the Metropolitan Life Insurance Company data published in 1959 and 1983. However, these tables were subject to a selection bias and included the notion of body frame size, making their use somewhat subjective. The subsequent adoption of BMI as a weight measurement tool has allowed organizations and experts to define an objective measurement tool as well as a standardized definition of normal weight range.
BMI is calculated by dividing weight in kilograms by the height in meters squared. Normal weight has a BMI ranging from 18.5 to 24.9 kg/m 2 . A BMI under 18.5 is considered underweight while a BMI of 25 to 29.9 is defined as overweight. An individual is obese when their BMI is 30. There are 3 grades of obesity: grade 1 (BMI ranging from 30 to 34.9), grade 2 (BMI ranging from 35.0 to 39.9), and grade 3 (BMI ≥40) ( Table 1 ).
| Body Mass Index (kg/m 2 ) | |
|---|---|
| Underweight | <18.5 |
| Normal weight range | 18.5–24.9 |
| Overweight | >25 |
| Pre-obesity | 25–29.9 |
| Obesity | >30 |
| Grade 1 obesity | 30–34.9 |
| Grade 2 obesity | 35–39.9 |
| Grade 3 (morbid) obesity | >40 |
Epidemiology
For the past 20 years, scientific literature referring to the management of obesity typically included an introductory statement resembling the following: “obesity is becoming a health issue of epidemic proportions.” However, this is no longer the case. Obesity is no longer a developing health issue; it is a well-established pandemic that affected countries have not been able to tackle.
The past 2 to 3 decades have witnessed the development of a new field in surgery (bariatric surgery) directed at treating the most severe cases of obesity (BMI >35 or 40). This progress has included the creation of specialized centers, surgical fellowships, and scientific peer-reviewed journals devoted to the field.
However, the vast majority of patients do not qualify for such extreme surgical methods, and national or international attempts to deal with this disease have had little effect. As an illustration, 10 years ago the United States Department of Health and Human Services launched Healthy People 2010, a nationwide health promotion and disease prevention agenda. The objectives of this project included addressing the issue of obesity and were developed with the Food and Drug Administration (FDA) and the National Institutes of Health (NIH). The aim was to promote health and reduce chronic disease associated with diet and weight in the United States, and included the following objectives to be achieved between 1999 and 2010:
- 1.
Increase the proportion of adults who are at a healthy weight (BMI between 18.5 and 25) from 42% to 60%
- 2.
Reduce the proportion of adults who are obese from 23% (data source: National Health and Nutrition Examination Survey [NHANES], Centers for Disease Control and Prevention [CDC], National Center for Health Statistics [NCHS]) to 15%
- 3.
Reduce the proportion of children and adolescents who are overweight or obese from 11% (data source: NHANES, CDC, NCHS) to 5%.
At the same time (2001) the United States Surgeon General launched an “effort to develop an action plan to combat overweight/obesity.”
Ten years after this nationwide effort, and as the 2020 version of this agenda is under way, none of these objectives have been achieved. Furthermore, the latest data from the same source state that the increase in obesity prevalence is continuing at the same rate, and shows the following numbers for each objective for 2007 to 2008:
- 1.
The proportion of adults who are at a healthy weight (BMI between 18.5 and 25) has decreased from 42% to 32% (goal was 60%)
- 2.
The proportion of adults who are obese has increased from 23% (data source: NHANES, CDC, NCHS) to 33.8% (goal was 15%)
- 3.
The proportion of overweight or obese children and adolescents has increased from 11% (data source: NHANES, CDC, NCHS) to 16.9% (goal was 5%).
As one of the nations most heavily affected by obesity, these statistics for the United States demonstrate not only the magnitude of this disease but also the daunting task awaiting those who try to reverse the current trend.
International Data
Like the United States, much of the rest of the world is also widely affected and is facing similarly ineffective calls for action: the World Health Organization (WHO) report entitled Obesity: Preventing and Managing the Global Epidemic was published 10 years ago, and worldwide prevalence of overweight and obesity have been continuously rising. According to the WHO, 1.6 billion adults worldwide were overweight in 2005 and 400 million were obese, and estimations for 2015 are 2.3 billion and 700 million, respectively.
It is interesting that the United States is not the first country in terms of prevalence of obesity according to WHO data. The Pacific islands have a prevalence of obesity ranging from 40% in French Polynesia, to 78.5% in Nauru, followed by Saudi Arabia (35%), the United States (34%), countries of the Arabic peninsula (28%–33%), and New Zealand (26.5%).
Data comparison among countries remains limited, essentially because of differences in methodology of data collection, and most studies rely on telephonic surveys, gathering self-reported weights known to fault by underestimation. For example, the Australian National Health Service measured data for 2007 to 2008 and reported 25% of adults as being obese, whereas self-reported BMI results from the survey showed “only” 21% of adults to be obese.
Europe
Obesity was reported in 9.8% of Italian adults in 2005, 12.9% of German adults in 2003, and 16.9% of French adults in 2006. In the United Kingdom, 24% of adults were classified as obese in 2006, compared with 15% in 1993. The lowest incidence is found in Switzerland, with 8.1% in 2007.
Asia
Many Asian countries have a low prevalence of obesity as defined by the BMI categories, yet high rates of obesity-related diseases. In Japan, the prevalence of obesity was 3.1% in 2000, whereas China reported a prevalence of obesity of 2.9% for 2002, and only 0.46% of Vietnamese adults were obese in 2000. However, a recent WHO expert panel concluded that Asians generally have a higher percentage of body fat than Caucasians of the same age, sex, and BMI. Also, the proportion of Asian people with risk factors for type 2 diabetes and cardiovascular disease is substantial even if below the existing WHO BMI cutoff point of 25. Indeed the WHO guidelines defining these cutoff points were based on data from Western countries. Therefore, a BMI greater than 23 is being considered as a potential threshold for increased weight-related health risk in these populations.
Developing countries
Obesity is becoming a burden even in developing countries that are still struggling with malnutrition, with increasing prevalence particularly in urban areas. This phenomenon has been called the “double burden” of disease. The WHO warns that the future burden of obesity and diabetes will significantly affect developing countries, and the projected numbers of new cases of diabetes run into the hundreds of millions within the next 2 decades.
Epidemiology
For the past 20 years, scientific literature referring to the management of obesity typically included an introductory statement resembling the following: “obesity is becoming a health issue of epidemic proportions.” However, this is no longer the case. Obesity is no longer a developing health issue; it is a well-established pandemic that affected countries have not been able to tackle.
The past 2 to 3 decades have witnessed the development of a new field in surgery (bariatric surgery) directed at treating the most severe cases of obesity (BMI >35 or 40). This progress has included the creation of specialized centers, surgical fellowships, and scientific peer-reviewed journals devoted to the field.
However, the vast majority of patients do not qualify for such extreme surgical methods, and national or international attempts to deal with this disease have had little effect. As an illustration, 10 years ago the United States Department of Health and Human Services launched Healthy People 2010, a nationwide health promotion and disease prevention agenda. The objectives of this project included addressing the issue of obesity and were developed with the Food and Drug Administration (FDA) and the National Institutes of Health (NIH). The aim was to promote health and reduce chronic disease associated with diet and weight in the United States, and included the following objectives to be achieved between 1999 and 2010:
- 1.
Increase the proportion of adults who are at a healthy weight (BMI between 18.5 and 25) from 42% to 60%
- 2.
Reduce the proportion of adults who are obese from 23% (data source: National Health and Nutrition Examination Survey [NHANES], Centers for Disease Control and Prevention [CDC], National Center for Health Statistics [NCHS]) to 15%
- 3.
Reduce the proportion of children and adolescents who are overweight or obese from 11% (data source: NHANES, CDC, NCHS) to 5%.
At the same time (2001) the United States Surgeon General launched an “effort to develop an action plan to combat overweight/obesity.”
Ten years after this nationwide effort, and as the 2020 version of this agenda is under way, none of these objectives have been achieved. Furthermore, the latest data from the same source state that the increase in obesity prevalence is continuing at the same rate, and shows the following numbers for each objective for 2007 to 2008:
- 1.
The proportion of adults who are at a healthy weight (BMI between 18.5 and 25) has decreased from 42% to 32% (goal was 60%)
- 2.
The proportion of adults who are obese has increased from 23% (data source: NHANES, CDC, NCHS) to 33.8% (goal was 15%)
- 3.
The proportion of overweight or obese children and adolescents has increased from 11% (data source: NHANES, CDC, NCHS) to 16.9% (goal was 5%).
As one of the nations most heavily affected by obesity, these statistics for the United States demonstrate not only the magnitude of this disease but also the daunting task awaiting those who try to reverse the current trend.
International Data
Like the United States, much of the rest of the world is also widely affected and is facing similarly ineffective calls for action: the World Health Organization (WHO) report entitled Obesity: Preventing and Managing the Global Epidemic was published 10 years ago, and worldwide prevalence of overweight and obesity have been continuously rising. According to the WHO, 1.6 billion adults worldwide were overweight in 2005 and 400 million were obese, and estimations for 2015 are 2.3 billion and 700 million, respectively.
It is interesting that the United States is not the first country in terms of prevalence of obesity according to WHO data. The Pacific islands have a prevalence of obesity ranging from 40% in French Polynesia, to 78.5% in Nauru, followed by Saudi Arabia (35%), the United States (34%), countries of the Arabic peninsula (28%–33%), and New Zealand (26.5%).
Data comparison among countries remains limited, essentially because of differences in methodology of data collection, and most studies rely on telephonic surveys, gathering self-reported weights known to fault by underestimation. For example, the Australian National Health Service measured data for 2007 to 2008 and reported 25% of adults as being obese, whereas self-reported BMI results from the survey showed “only” 21% of adults to be obese.
Europe
Obesity was reported in 9.8% of Italian adults in 2005, 12.9% of German adults in 2003, and 16.9% of French adults in 2006. In the United Kingdom, 24% of adults were classified as obese in 2006, compared with 15% in 1993. The lowest incidence is found in Switzerland, with 8.1% in 2007.
Asia
Many Asian countries have a low prevalence of obesity as defined by the BMI categories, yet high rates of obesity-related diseases. In Japan, the prevalence of obesity was 3.1% in 2000, whereas China reported a prevalence of obesity of 2.9% for 2002, and only 0.46% of Vietnamese adults were obese in 2000. However, a recent WHO expert panel concluded that Asians generally have a higher percentage of body fat than Caucasians of the same age, sex, and BMI. Also, the proportion of Asian people with risk factors for type 2 diabetes and cardiovascular disease is substantial even if below the existing WHO BMI cutoff point of 25. Indeed the WHO guidelines defining these cutoff points were based on data from Western countries. Therefore, a BMI greater than 23 is being considered as a potential threshold for increased weight-related health risk in these populations.
Developing countries
Obesity is becoming a burden even in developing countries that are still struggling with malnutrition, with increasing prevalence particularly in urban areas. This phenomenon has been called the “double burden” of disease. The WHO warns that the future burden of obesity and diabetes will significantly affect developing countries, and the projected numbers of new cases of diabetes run into the hundreds of millions within the next 2 decades.
Mortality and comorbid disease
The WHO has analyzed the attributable number of deaths by risk factor around the world : In 2004, obesity and overweight accounted for 11.4% of deaths in Europe and 9.5% of deaths in America (continent). In Europe, this was secondary only to high blood pressure (26.2%) and tobacco use (15.5%).
Little controversy remains regarding the relationship between obesity and increased incidence of comorbidities and mortality. The Framingham study in 1985 attributed a 3.9-times higher 30-year mortality rate to (nonsmoking) overweight men compared with nonobese men. An analysis of this study demonstrated that a 40 year-old female nonsmoker loses 3.3 years and a male nonsmoker loses 3.1 years of life expectancy because of overweight. An obese female nonsmoker loses 7.1 years and males lose 5.8 years of life expectancy.
In the recent past, some argument has remained as for the existence of a direct causative relationship between high BMI and increased mortality, and separating obesity from other closely related risk factors remains controversial. For example, a large cohort study of more than 20,000 patients has demonstrated that lean but unfit subjects had an overall mortality risk ratio double that of cardiorespiratorily fit obese patient (relative risk 2.06 vs 0.93) and comparable to unfit obese subjects (relative risk 1.92). It now seems clear, however, that even if different risk factors intertwine and potentiate each other, and direct causality is not established, obesity is clearly related to a significant increase in overall mortality and specific comorbid diseases.
Some of the largest and most recent studies regarding BMI and mortality have not only demonstrated that obesity shortens life expectancy but also the linear relationship between the two. An analysis of 900,000 adults demonstrated that each 5 kg/m 2 higher BMI was on average associated with about 30% higher overall mortality ; and a study of nearly 1.5 million white adults reported that mortality increased both above a BMI of 25 and below a BMI of 20, with a hazard ratio of 2.51 in women with a BMI above 40 when compared with women with a BMI between 20 and 25. In western Europe in 2000, 77% of subjects with a normal BMI are alive at age 70 years, but only 49% of subjects with a BMI between 40 and 50. Mortality from all causes was increased in obese patients, but cardiovascular death was the most important, followed by diabetes related death.
Comorbid Disease
Just as the relative role of each risk factor in increased mortality for overweight and obese patients is difficult to quantify, so is the causality of obesity in the existence of comorbid conditions. Yet the association of obesity with multiple comorbidities is clearly evident. A recent meta-analysis reviewed the associated risk of obesity and 18 comorbid conditions. The investigators found a positive association with 15 diseases, including type 2 diabetes; 6 cancer types: breast (postmenopausal), colorectal, endometrial, kidney, ovarian, and pancreatic; coronary artery disease; hypertension; pulmonary embolism; stroke; and asthma. These results are detailed in Table 2 .
Related posts:
Medical Therapy for Obesity
Presurgical Evaluation and Postoperative Care for the Bariatric Patient
Medical Management of Postsurgical Complications: The Bariatric Surgeon’s Perspective
Management of Acute Postoperative Hemorrhage in the Bariatric Patient
Accessing the Pancreatobiliary Limb and ERCP in the Bariatric Patient
Management of Postsurgical Leaks in the Bariatric Patient
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
