• Body mass index (BMI) is calculated as weight in kilograms divided by height in meters squared (kg/m2). BMI is currently the preferred method for determining whether a patient is obese.
• Patients with a BMI of 30 or greater are considered obese; those with a BMI between 25 and 29.9 are considered overweight. For Asians, overweight is a BMI between 23 and 24.9 kg/m2 and obesity a BMI > 25 kg/m2.
• Abdominal circumference should also be measured to assess for abdominal obesity.
• A waist circumference of > 102 cm (40 in) in men or > 88 cm (35 in) in women is considered indicative of abdominal obesity. A waist circumference of > 80 cm in Asian females and > 90 cm in Asian males is considered abnormal.
• Treatment of patients with obesity requires a multidisciplinary team approach.
• Lifestyle modifications, including dietary changes and increased physical activity, remain first-line treatment for patients with obesity.
• Adjuvant pharmacotherapy may be considered for patients with a BMI greater than 30 kg/m2 or a BMI of 27 to 30 kg/m2 with concomitant weight-related complications.
• Bariatric surgery should be considered for patients with a BMI of 40 kg/m2 or greater and for those with a BMI of 35 kg/m2 or greater who have significant comorbidities such as severe diabetes, sleep apnea, or joint disease after nonsurgical weight loss attempts have failed.
Obesity is a complex disease that represents a growing epidemic in the United States and worldwide. In the 2013–2014 National Health and Nutrition Examination Survey (NHANES), 35% of adult men and 40.4% of adult women were noted to be obese. The prevalence of obesity has increased among women from 2005 to 2014 but has not changed in men. There are disparities in the prevalence of obesity between ethnic groups, especially among women. In the United States, the prevalence of obesity is highest in non-Hispanic black women. The American Medical Association recently officially classified obesity as a disease due to its association with several comorbidities and increased mortality.
Obesity is a condition marked by the accumulation of excess body fat. The body mass index (BMI) is the most practical way to evaluate the degree of excess weight. It is calculated from the weight (in kilograms) and the square of the height (in meters), as follows:
The World Health Organization (WHO) and National Institutes of Health (NIH) define overweight as a BMI between 25 and 29.9 kg/m2 and obesity as a BMI equal to greater than 30 kg/m2 (Table 1). These guidelines apply to whites, Hispanics, and blacks. Because Asians can have higher percentage of body fat at a lower BMI, overweight for this particular ethnic group is a BMI between 23 and 24.9 kg/m2, and obesity is a BMI equal to or greater than 25 kg/m2. The BMI correlates with percentage of body fat and body fat mass as well as with mortality. The BMI may however overestimate the degree of body fat in athletes. However, for a given BMI, the degree of body fatness tends to be higher in women compared with men, and it is higher in older compared with younger people. The relationship between BMI and mortality appears to form a J- or U-shaped curve, with the lowest mortality rate seen in those with a BMI of about 25 kg/m2 (Figure 1).
FIGURE 1 All-cause mortality versus body mass index (BMI) for each sex in the range of 15–50 kg/m2 (excluding the first 5 years of follow-up). (From Whitlock G, Lewington S, Sherliker P, et al: Body-mass index and cause- specific mortality in 900,000 adults: Collaborative analyses of 57 prospective studies. Lancet 2009;373:1083–1096).
Classification of Overweight and Obesity by BMI, Waist Circumference, and Associated Health Risk
Reproduced from Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: The evidence report. National Institutes of Health. Obes Res 1998;6(Suppl 2):51S–209S.
* Disease risk for type 2 diabetes, hypertension, and cardiovascular disease relative to normal weight and waist circumference.
† Increased waist circumference can also be a marker for increased risk even in persons of normal weight.
Because people with abdominal (central) adiposity are more likely to develop many of the health conditions associated with obesity, waist circumference is an important adjuvant measurement to obtain when screening for obesity. Waist circumference is measured at the level of the top of the iliac crest with the measuring tape snug against the skin. In adults with a BMI of 25 to 34.9 kg/m2, a waist circumference greater than 102 cm (40 in) for men and 88 cm (35 in) for women is associated with a greater risk of hypertension, type 2 diabetes, dyslipidemia, and coronary heart disease (CHD) (see Table 1). In patients with a BMI ≥ 35 kg/m2, measurement of waist circumference is less helpful because it adds little to the predictive power of the disease risk classification of BMI; almost all individuals with this BMI also have an abnormal waist circumference. More precise measurement of abdominal fat can be made with abdominal computed tomography or magnetic resonance imaging. Alternative methods to assess body composition and degree of fatness include measurements of skin fold thickness, hydrostatic weighing, bioelectric impedance, and scanning by dual-energy x-ray absorptiometry. These methods require specialized equipment and trained personnel and are not used routinely in clinical practice.
Etiology and Pathophysiology
Obesity is a complex, multifactorial disease characterized by excessive caloric consumption and inadequate caloric expenditure. Many factors, including genetic and environmental influences, can contribute to the development of obesity. However, personal decisions regarding food choices, portion sizes, and level of activity also contribute to body size.
When evaluating a patient with obesity, it is important to rule out disorders such as Cushing’s syndrome and hypothyroidism. Because many medications promote weight gain, including several antipsychotics, antidepressants, antiepileptics, sulfonylureas, and steroids (Table 2), it is prudent to obtain a complete medication history from any patient who is being evaluated for obesity. Single- gene mutations (e.g., in the melanocortin 4 receptor gene and leptin gene) and congenital syndromes (e.g., Prader-Willi, Bardet-Biedel, Cohen) typically cause early-onset obesity before 5 years of age.
Drugs that Cause Weight Gain and Some Alternatives
Copyright ©2001 George A Bray, MD. Reproduced with permission.
1 Not available in the United States.
Obesity is associated with a variety of other medical conditions that can increase morbidity and mortality. Comorbidities associated with obesity include metabolic syndrome and insulin resistance, type 2 diabetes, dyslipidemia, hypertension, coronary artery disease, degenerative joint disease, nonalcoholic fatty liver disease (NAFLD), and obstructive sleep apnea.
Insulin Resistance and Metabolic Syndrome
Insulin resistance is defined as a subnormal response to endogenous insulin. This results in pancreatic B-cell compensation with hypersecretion of insulin. Insulin resistance leads to various components of the metabolic syndrome, including low HDL cholesterol, high triglycerides, elevated blood pressure, and hyperglycemia. Patients may also manifest acanthosis nigricans and skin tags.
Type 2 Diabetes
The increasing prevalence of obesity has also resulted in an increasing prevalence of type 2 diabetes. More than 80% of type 2 diabetes can be attributed to obesity, but other factors, such as family history, are also involved. Criteria for the diagnosis of type 2 diabetes include a fasting glucose level greater than 125 mg/dL or glucose levels greater than 200 mg/dL during a 2-hour oral glucose tolerance test.
Hypertension is a common chronic disease, and it has been estimated that obesity is a major risk factor for hypertension. Hypertension is associated with an increased risk for stroke, myocardial infarction, heart failure, and kidney disease. Even a modest weight loss (5%–10% of initial weight) can lead to a significant fall in blood pressure and, often, decreased need for antihypertensive medications.
A variety of blood lipid abnormalities are seen frequently in obese patients. These include elevated levels of total cholesterol, LDL cholesterol, and triglycerides and decreased levels of HDL cholesterol. Patients with central adiposity are at particularly high risk for the development of hypertriglyceridemia and low HDL. Screening for dyslipidemia should be done with a fasting lipid profile. However, if the testing opportunity is nonfasting, the total cholesterol and HDL values can still be measured.
Coronary Heart Disease
Comorbidities associated with obesity such as hypertension, insulin resistance, type 2 diabetes, and dyslipidemia lead to increased risk of cardiovascular disease in obese adults. Obesity is also associated with increased risk of CHD, heart failure, cardiovascular mortality, and all- cause mortality.
Obstructive sleep apnea is the most important respiratory problem associated with obesity. It is often underrecognized and inadequately treated. Patients may present with snoring, apneic episodes, excessive daytime somnolence, fatigue, irritability, and erectile dysfunction.
Consequent nocturnal hypoxemia may result in arrhythmias, pulmonary hypertension, and right-sided heart failure. Treatment includes weight loss and use of continuous positive airway pressure at night. Other alterations in pulmonary function that may occur, include higher residual lung volume associated with increased abdominal pressure on the diaphragm, decreased lung compliance and increased chest wall impedance, ventilation-perfusion abnormalities, reduced strength and endurance of respiratory muscles, depressed ventilatory drive, and bronchospasm.
Obesity is associated with an increased risk of gastroesophageal reflux disease symptoms as well as erosive esophagitis, esophageal adenocarcinoma, and gastric carcinoma. It has been suggested that increased intragastric pressure and relaxation of the lower esophageal sphincter from gastric compression from surrounding adiposity contributes to the reflux rather than the type of diet consumed.
Obesity increases the risk of cholelithiasis and of NAFLD. The spectrum of NAFLD ranges from steatosis with mild disruption of the liver architecture by fat to steatohepatitis with varying degrees of fibrosis and cirrhosis. Increased liver transaminase levels and findings of steatosis on ultrasonography are both suggestive of NAFLD in obese patients. However, the definitive diagnosis remains histologic.
The incidence of osteoarthritis is increased in obese subjects. Osteoarthritis commonly develops in the knees and ankles but can also affect non–weight-bearing joints. Weight loss results in decreased risk of osteoarthritis.
For both men and women, increased BMI is associated with increased mortality from several cancers, such as those of the esophagus, colon and rectum, liver, gallbladder, pancreas, and kidney, as well as non- Hodgkin lymphoma and multiple myeloma. Additionally, obese men are at increased risk of death from stomach and prostate cancer, and obese women are at increased risk of death from cancers of the breast, uterus, cervix, and ovary.
Obese subjects often are subjected to discrimination in education, employment, and health care. Overweight women have been noted to have lower household incomes and higher rates of household poverty than women who were not overweight, independent of their baseline socioeconomic status and aptitude test scores. Depression has also been seen in association with severe obesity, particularly in younger patients and in women.
Economic Consequences of Obesity
Overweight and obesity and their associated health problems have a significant economic impact on the health care system. Health care costs are higher in obese subjects compared to their normal weight counterparts. The higher costs are predominantly explained by the presence of CHD, hypertension, and diabetes.
Patients must undergo a detailed history and physical examination before a treatment plan is initiated. Secondary causes of obesity, such as Cushing’s syndrome and hypothyroidism, should be considered in the evaluation. A complete medication history is crucial to determining whether any medications may have promoted weight gain.
Laboratory studies should be directed at ruling out secondary causes in selected patients and ruling out comorbidities (fasting glucose, lipid profile, liver function tests). It is important that practitioners assess each patient’s willingness to change and expectations for weight loss. Treatment should be based on the patient’s BMI, risk factors, and willingness to lose weight. Patients who are in the precontemplative phase (i.e., in the early stages of thinking about it) are not likely to be successful despite appropriate counseling. Health care providers must enforce the idea that even a modest weight loss improves complications associated with obesity.
Treatment of obesity requires a multidisciplinary team approach.
Lifestyle modifications, including dietary change and increased physical activity, represent first-line treatment for patients with obesity. Pharmacotherapy and bariatric surgery may be used as adjuvant therapies in certain patients.
The goal of treatment is to prevent the complications of obesity. The initial target goal of weight loss therapy is to decrease body weight by 5% to 10%. Once this target is achieved, further weight loss can be attempted if indicated. The rationales for this initial goal of moderate weight loss are that:
• It can decrease the severity of obesity-associated risk factors.
• It can set the stage for further weight loss, if indicated.
• It is realistic and can be achieved and maintained over time.
A reasonable timeline for a 5% to 10% reduction in body weight is 6 months of therapy. A period of weight maintenance should then occur. Further weight loss may be considered if the initial goal is achieved and then maintained for at least 6 months. It is important to inform patients that it is preferable to maintain a moderate amount of weight loss over time than to lose more weight but later regain it.
Behavior modification is an integral part of any weight loss program. Motivational interviewing (MI) is a client-centered, collaborative decision-making approach that is helpful in facilitating lifestyle modifications. MI helps the health care provider provide nonjudgmental feedback to patients, allowing for patients’ resistance to change and encouraging patients to develop their own arguments for engaging in health behavior change.
The goal of behavioral therapy is to help patients make long-term changes in their eating behavior by modifying and monitoring their food intake, increasing their physical activity, and controlling cues and stimuli in the environment that trigger eating. Maintaining food diaries and activity records for self-monitoring are key elements in any successful behavioral weight loss program. Stimulus control is considered a key element in a behavioral program. It focuses on gaining control over the environmental factors that activate eating and eliminating or modifying the environmental factors that facilitate overeating.
This requires the availability of trained personnel such as psychologists and therapists. The behavioral strategies taught are aimed at decreasing caloric intake and increasing physical activity in the long term.
The goal of dietary therapy, therefore, is to reduce the total number of calories consumed. A principal determinant of weight loss appears to be the degree of adherence to the diet, irrespective of the particular macronutrient composition. Recent data suggest that the so-called Mediterranean diet and low-carbohydrate diets may represent effective alternatives to the low-fat diet for weight loss. Thus, the macronutrient mix of the diet should be based upon patient preferences in order to improve long-term adherence. Often patients revert to their previous habit of eating and can regain the weight that was lost. Diets that incorporate the patient’s preference and culture to find the optimal mix of macronutrients will have the best chance of success.
Approximately 22 kcal/kg is required to maintain a kilogram of body weight in a normal adult. Thus, the expected or calculated energy expenditure for a woman weighing 100 kg is approximately 2200 kcal/day. The variability of ± 20% could give energy needs as high as 2620 kcal/day or as low as 1860 kcal/day. An average deficit of 500 kcal/day should result in an initial weight loss of approximately 0.5 kg/week (1 lb/week). However, after 3 to 6 months of weight loss, energy expenditure adaptations occur, which slow the body weight response to a given change in energy intake, thereby diminishing ongoing weight loss.
Patients should be counseled to avoid unnecessary calories from alcohol and sugary beverages such as soda and juice.
Very–low-calorie diets contain less than 800 kcal/day and are usually administered in the form of liquid supplements. Although these diets do produce significant and rapid weight loss, results are difficult to maintain in the long term. These diets require close monitoring by a health care professional. Side effects associated with very–low-calorie diets include fatigue, constipation, hair loss, and gallstones. These diets are strictly contraindicated in children and in pregnant and lactating women and are generally reserved for patients who require rapid weight loss for a specific purpose such as surgery.
Physical activity is an integral component of therapy for obese patients and is most important in the prevention of weight regain. Physical activity also decreases the risks for cardiovascular disease and type 2 diabetes. Sedentary obese patients need to start their exercise program slowly and may require supervision from a health care professional. Initially, patients may be encouraged to increase their activities of daily living. For example, it may be suggested that they take the stairs instead of the elevator or that they park farther away from work or shopping. The intensity and duration of exercise should be increased gradually over time, with a goal of achieving 30 minutes of moderate-intensity activity on most days of the week to improve health (150 minutes/week) and 60 minutes of exercise of most days of the week to control body weight.
Ideally, adults should also perform muscle-strengthening exercises on 2 or more days per week. Patients should be encouraged to choose activities that they enjoy and to build these activities into their daily schedule. Sedentary activities, such as watching television, sitting in front of a computer screen, and playing video games, should be discouraged.
Pharmacotherapy (Table 3) is usually reserved for patients with a BMI greater than 30 kg/m2 without complications or a BMI greater than 27 to 30 kg/m2 with concomitant weight-related complications. These patients should have failed to achieve weight loss goals through diet and exercise alone. Pharmacotherapy must be used in conjunction with a program that includes dietary changes and physical activity.
Drugs Approved by the FDA for Treatment of Obesity
1 Not available in the United States.
* Maintenance dose.
The success may be measured by the degree of weight loss and improvement in associated risk factors. Weight loss should be more than 5% below baseline to be considered effective. A weight loss of 5% to 10% can significantly reduce the baseline risk factors for diabetes and cardiovascular disease and improvement in baseline risk factors after weight loss is an important criterion in the determination of whether to continue therapy.
Orlistat (Xenical) is recommended as the first-line drug for patients with dyslipidemia and/or diabetes. Orlistat is an inhibitor of pancreatic lipases that causes weight loss by limiting fat absorption. The recommended dose for adults is 120 mg PO three times daily with meals. A lower dose of 60 mg preparation (Alli) is available over the counter in the United States and several other countries. Orlistat has been shown to be effective for weight loss and prevention of weight regain. In a meta-analysis of 12 trials that included patients with and without diabetes and reported data with 12-month outcomes, patients randomly assigned to orlistat plus a behavioral intervention lost 5 to 10 kg (8% of baseline weight) compared with 3 to 6 kg in the control group (placebo plus behavioral intervention), for a mean placebo- subtracted difference of 3 kg. Weight loss was maintained with up to 24 to 36 months of orlistat treatment. Orlistat has also been shown to result in improved metabolic outcomes such as delay in development of type 2 diabetes in those that have impaired fasting glucose and improvement in blood pressure in hypertensive patients and in serum total and LDL cholesterol levels. Side effects associated with orlistat are mostly gastrointestinal and include cramping, flatus, fecal incontinence, oily spotting, and flatus with discharge. These side effects tend to decrease over time as patients learn to restrict their dietary intake to less than 30% fat. Severe cases of liver damage have been reported in patients taking orlistat. Orlistat may also interfere with the absorption of fat-soluble vitamins, so the use of a daily multivitamin supplement at bedtime is recommended.
Lorcaserin hydrochloride (Belviq) is a serotonin 2C receptor agonist that causes weight loss by causing appetite suppression. It appears to have fewer adverse effects than orlistat, although long-term safety data are limited. The recommended dosage is 10 mg twice daily.
Lorcaserin should be discontinued if patients do not lose 5% of their body weight in 12 weeks. The efficacy of lorcaserin appears similar to that of orlistat (mean difference in weight loss between active and placebo-treated groups approximately 3–4 kg). Common side effects include nausea, headache, dizziness, nasopharyngitis, and fatigue.
Lorcaserin may increase the risk of symptomatic hypoglycemia in patients with type 2 diabetes on oral agents, necessitating a reduction in the dose of diabetes medications. Lorcaserin should not be used in individuals with creatinine clearance < 30 mL/minute. It is contraindicated during pregnancy. In addition, lorcaserin should not be used with other serotonergic drugs (e.g., selective serotonin reuptake inhibitors, selective serotonin-norepinephrine reuptake inhibitors, bupropion [Wellbutrin], tricyclic antidepressants, and monamine oxidase inhibitors) because of the theoretical potential for serotonin syndrome.
Qsymia is a combination of phentermine (Adipex-P), an appetite suppressant, and topiramate, a medication used to treat epilepsy and migraine. The initial dose of phentermine/topiramate is 3.75/23 mg for 14 days, followed by 7.5/46 mg thereafter. If after 12 weeks, a 3% loss in body weight is not achieved, the dose can be increased to 11.25/69 mg for 14 days, and then to 15/92 mg daily. If an individual does not lose 5% of body weight after 12 weeks on the highest dose, phentermine/topiramate should be discontinued gradually, as abrupt withdrawal of topiramate can cause seizures. Qsymia is contraindicated during pregnancy due to an increased risk of orofacial clefts in infants exposed to the combination drug during the first trimester of pregnancy. Women of child-bearing age should have a pregnancy test before starting this drug and monthly thereafter. It is also contraindicated in patients with glaucoma, hyperthyroidism, and individuals who have taken monoamine oxidase inhibitors within 14 days. Clinicians who prescribe phentermine/topiramate are encouraged to enroll in a risk evaluation and mitigation strategy, which includes an online or print formal training module detailing safety information. Pharmacies that dispense Qsymia also require a specific certification and have to provide patients with a medication guide and brochure each time the drug is dispensed, detailing the risks of birth defects.
Side effects for Qsymia include tachycardia, paresthesias, dizziness, altered taste sensation, insomnia, and constipation. Qsymia is not recommended in patients with cardiovascular disease (hypertension or CHD) and may be considered for obese postmenopausal women and men without cardiovascular disease, particularly those who do not tolerate orlistat or lorcaserin.
Contrave, a combination of bupropion, an antidepressant/anorexiant with naltrexone, an opioid-receptor antagonist was approved by the Food and Drug Administration in September 2014 as an adjunct to diet and exercise in patients with BMI ≥30 kg/m2 (or ≥27 kg/m2 with comorbidities). The initial dose is one tablet (8 mg of naltrexone and 90 mg of bupropion) daily. After one week, the dose is increased to one tablet twice daily, and by week four to two tablets twice daily. If after 12 weeks the patient has not lost at least 5 percent of baseline body weight, the drug should be discontinued because benefit is unlikely. Contraindications include concomitant use of other bupropion-containing products, chronic opioid use, uncontrolled hypertension, eating disorder, seizure disorders, and use within 14 days of taking monoamine oxidase inhibitors. Side effects for bupropion-naltrexone include nausea, headache, constipation, insomnia vomiting, constipation, dizziness, and dry mouth.
Liraglutide (Saxenda) is a long acting glucagon-like polypeptide-1 (GLP-1) receptor agonist that is recommended for chronic weight management in conjunction with reduced-calorie diet and physical activity. It is recommended for patients with BMI ≥30 kg/m2 or ≥27 kg/m2 if one weight-related comorbidity is present. Liraglutide is administered subcutaneously in the abdomen, thigh, or upper arm once daily. The initial dose is 0.6 mg daily for one week. The dose can be increased at weekly intervals (1.2, 1.8, 2.4 mg) to the recommended dose of 3 mg. If after 16 weeks a patient has not lost at least 4 percent of baseline body weight, liraglutide should be discontinued, as it is unlikely the patient will achieve clinically meaningful weight loss with continued treatment. Liraglutide is contraindicated in those with a personal history or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 or 2B. Side effects for liraglutide include headache, nausea, vomiting, diarrhea, and constipation which tend to be dose-related. Hypoglycemia can occur in non-diabetics but at a lower frequency than type 2 diabetics.
Several sympathomimetic drugs (phentermine, benzphetamine [Didrex], diethylpropion [Tenuate], and phendimetrazine [Bontril PDM]) are approved for the short-term (up to 12 weeks) treatment of obesity. These drugs can increase blood pressure and have a potential for abuse and therefore are contraindicated in patients with CHD, hypertension, or hyperthyroidism or in patients with a history of drug abuse.
Vagal blockade device is available in the United States for the treatment of adults with a BMI of 40 to 45 kg/m2 or of 35 to 39.9 kg/m2 with at least one obesity-related comorbidity (e.g., type 2 diabetes) who have failed a supervised weight management program within the past five years. The abdominal vagal nerve controls gastric emptying and signals the satiety center in the brain. Electric stimulation of the abdominal vagal nerve from the subcutaneously implanted device blocks vagal nerve conduction between the brain and the stomach, thereby reducing hunger. However, the specific mechanism for weight loss is unknown. Implantation of the device involves laparoscopically placing one lead on the anterior vagal trunk and the other on the posterior intra-abdominal vagal trunk. Adverse events include pain at the neuroregulator site, vomiting, surgical complications, nausea, heartburn, belching and dysphagia.
Implantation of the device is contraindicated in patients at high risk for surgical complications, patients with other permanent implanted devices (e.g., heart pacemaker, implanted defibrillator, neurostimulator), or patients likely to need magnetic resonance imaging (MRI) procedures.
Bariatric surgery should be considered for patients with a BMI greater than 40 kg/m2 or a BMI greater than 35 kg/m2 with significant comorbid conditions. Patients should be well informed and motivated and have failed a trial of nonsurgical weight loss. They should also be of acceptable risk for surgery. Contraindications to bariatric surgery include untreated major depression or psychosis, binge eating disorders, active drug or alcohol abuse, and the inability to comply with nutritional requirements including lifelong vitamin supplementation. A comprehensive preoperative evaluation and close extended follow-up after surgery are required. Bariatric surgery has been shown to result in a significant and sustained weight loss as well as resolution of many obesity-related complications, in most patients. Patients may lose more than 60% of their excess weight after bariatric surgery. There is increasing interest in the role of bariatric surgery as a treatment for type 2 diabetes in obese patients who have a BMI less than 35 kg/m2. Several unblinded trials comparing bariatric surgery with medical therapy for type 2 diabetes have demonstrated significantly greater improvements in blood glucose control in patients who underwent bariatric surgery. However, long-term data are required before bariatric surgery procedures can be routinely recommended for the treatment of persistent hyperglycemia, resistant to multiple medications, in patients with mild obesity.
Bariatric procedures can be divided into three types: restrictive procedures, which decrease gastric volume and limit food intake; malabsorptive procedures, which alter digestion of food and decrease the effectiveness of nutrient absorption; and mixed procedures, which have components of both restriction and malabsorption. Currently, the most common procedures performed in the United States are the laparoscopic Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, and the laparoscopic adjustable band (a restrictive procedure) (Figure 2).
FIGURE 2 Techniques commonly used for the surgical treatment of obesity: Roux-en-Y gastric bypass (A), adjustable laparoscopic band (B), laparoscopic sleeve gastrectomy (C).
Roux-en-Y Gastric Bypass
The RYGB is characterized by a small (less than 30 mL) proximal gastric pouch that is divided and separated from the distal stomach and anastomosed to a Roux limb of small bowel, 75 to 150 cm in length. It is the most commonly performed bariatric procedure and involves the creation of a small pouch at the superior portion of the stomach. The pouch is then connected to the jejunum, bypassing the duodenum, where the majority of calories are absorbed. The mortality rate associated with gastric bypass is low (< 1%), but patients can have significant postoperative complications, including pulmonary emboli, deep vein thromboses, leaks from the gastrointestinal tract, gastric remnant distention, stomal stenosis, ulcers, gallstones, and hernias.
Patients are required to take lifelong vitamin and mineral supplementation because absorption of iron, vitamin B12/folate, and others are affected.
Laparoscopic Sleeve Gastrectomy
Laparoscopic sleeve gastrectomy (LSG), the second-most commonly performed bariatric procedure, is emerging as a single-stage bariatric procedure. It is a restrictive, nonreversible procedure involving removal of about 85% of the stomach so that the remainder takes the shape of a tube or sleeve. Recent studies have shown that LSG has equivalent results to other procedures. There is durability of results 5 to 9 years following the procedure, but there is no long-term data beyond this. Gastric-sleeve dilatations and staple-line leaks are the most common complications. LSG involves no foreign body, needs no invasive adjustments, and most likely avoids malabsorption of many micronutrients.
Laparoscopic Adjustable Gastric Band
Adjustable gastric banding is a purely restrictive procedure that compartmentalizes the upper stomach by placing a tight, adjustable prosthetic band around the entrance to the stomach. The gastric band consists of a soft, locking silicone ring that is connected to an infusion port placed in the subcutaneous tissue. The port can be accessed with a needle and syringe, and injection or removal of saline into the port may be used to manipulate the size of the band diameter, leading to greater or lesser degrees of restriction. Although weight loss with banding tends to be slower than with other weight loss procedures, the procedure is popular because it is performed laparoscopically and is reversible. Laparoscopic banding can also be associated with side effects such as stomal obstruction; band erosion, slippage, or prolapse; port malfunction; pouch or esophageal dilation; and infection.
The FDA has recently approved intragastric balloon devices to treat obesity in adults with a BMI ≥ 30 kg/m2 who have failed previous weight loss attempts. The balloon promotes sensation of satiety and therefore as the weight loss mechanism is primarily restrictive, the success is dependent on patient’s adherence to lifestyle modifications. Adults with a BMI ≥40 kg/m2 or a BMI ≥35 kg/m2 with one or more co-morbidities who qualify for bariatric surgery, but refuse or lack access to bariatric surgery, may also be considered for the balloon. The intragastric balloon IBD may serve as a bridging therapy in the extremely obese patient who is not a bariatric surgical candidate due to excessive anesthesia risk.
Several intragastric balloons are available and these differ in their volume, means of insertion and removal, duration in stomach and adjustability. Common initial symptoms include nausea, vomiting, reflux, and abdominal pain. These symptoms tends to diminish in most patients. Total weight loss is intermediate between bariatric surgery and medical measures including drugs and lifestyle modifications.
Aspiration therapy is approved by FDA for patients with BMI between 35–55 who have failed weight loss with nonsurgical therapy. Aspiration therapy induces weight loss by removing a portion of the ingested calories after each meal via a modified percutaneous endoscopic gastrostomy tube system. The patient is instructed to drain the stomach contents 20–30 min after each meal. There is lack of long term data on the efficacy of the aspiration therapy.
In conclusion, obesity is a growing public health problem that has significant short- and long-term consequences. Lifestyle modification with or without adjuvant therapies should be used to achieve a goal of modest weight loss. With modest weight loss, patients experience a decreased risk of mortality and improvement of obesity-related complications.
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