Bariatric Surgery for Weight Loss

Course #90982 - $20 • 5 Hours/Credits


Self-Assessment Questions

    1 . The American Society for Metabolic and Bariatric Surgery (ASMBS) estimates that bariatric surgery was performed on how many individuals with morbid obesity in 2016?
    A) 25,000
    B) 95,000
    C) 216,000
    D) 425,000

    EPIDEMIOLOGY

    With the substantial increase in the number of obese Americans over the past several decades, the use of bariatric surgery has increased as well. According to a statistical report from the Agency for Healthcare Research and Quality (AHRQ), the annual number of bariatric surgeries in the United States increased from 13,386 to 121,055 between 1998 and 2004, a change of more than 800% [23]. According to the American Society for Metabolic and Bariatric Surgery (ASMBS), the number of bariatric surgeries performed in the United States increased from 158,000 in 2011 to 216,000 in 2016, an increase of 27%, with the biggest jump occurring between 2015 and 2016 [24].

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    2 . The two most common types of bariatric surgery in the United States are
    A) vertical banded gastroplasty and biliopancreatic diversion.
    B) Roux-en-Y gastric bypass and vertical banded gastroplasty.
    C) laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass.
    D) vertical banded gastroplasty and the laparoscopic adjustable gastric band.

    BARIATRIC SURGERY

    Weight-loss surgeries most commonly used in the United States are the laparoscopic sleeve gastrectomy (LSG), or "sleeve," and Roux-en-Y gastric bypass (RYGB), surpassing the historically popular laparoscopic adjustable gastric band (LAGB), or "band." RYGB is a mixed restrictive/malabsorptive procedure, while LSG and LAGB are purely restrictive. Based on data from the University HealthSystem Consortium Clinical Database, gastric bypass made up 66% of bariatric surgeries performed at academic medical centers in 2007, while LAGB accounted for 23% [30]. By 2016, LSG had become the leading procedure performed, accounting for 58.1% of bariatric surgeries, compared with 17.8% in 2011 [24]. In 2016, RYGB comprised 18.7% and LAGB made up only 3.4% [24]. Certain other surgeries, previously common, have fallen out of favor due to high complication rates. They are described briefly in this course because patients who had these surgeries will still be seen in primary and specialty care. Many publications regarding bariatric surgery incorporate multiple procedures or variations on RYGB; as much as possible, the original terminology will be used when discussing each study.

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    3 . Which of the following procedures is considered strictly restrictive?
    A) Duodenal switch
    B) Biliopancreatic diversion (BPD)
    C) Roux-en-Y gastric bypass (RYGB)
    D) Laparoscopic sleeve gastrectomy (LSG)

    BARIATRIC SURGERY

    Weight-loss surgeries most commonly used in the United States are the laparoscopic sleeve gastrectomy (LSG), or "sleeve," and Roux-en-Y gastric bypass (RYGB), surpassing the historically popular laparoscopic adjustable gastric band (LAGB), or "band." RYGB is a mixed restrictive/malabsorptive procedure, while LSG and LAGB are purely restrictive. Based on data from the University HealthSystem Consortium Clinical Database, gastric bypass made up 66% of bariatric surgeries performed at academic medical centers in 2007, while LAGB accounted for 23% [30]. By 2016, LSG had become the leading procedure performed, accounting for 58.1% of bariatric surgeries, compared with 17.8% in 2011 [24]. In 2016, RYGB comprised 18.7% and LAGB made up only 3.4% [24]. Certain other surgeries, previously common, have fallen out of favor due to high complication rates. They are described briefly in this course because patients who had these surgeries will still be seen in primary and specialty care. Many publications regarding bariatric surgery incorporate multiple procedures or variations on RYGB; as much as possible, the original terminology will be used when discussing each study.

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    4 . According to the American Association of Clinical Endocrinologists, the Obesity Society, and the ASMBS, bariatric surgery may be an appropriate option for which of the following patients?
    A) A woman with BMI of 37 who has hypertension and impaired glucose tolerance.
    B) A man with BMI of 29 who has diabetes, dyslipidemia, and obstructive sleep apnea.
    C) A woman with BMI of 42 who is planning to attempt lifestyle changes for the first time.
    D) A woman with BMI of 36 who states that she wants the surgery because "I can't seem to control what I eat."

    BARIATRIC SURGERY

    In 2013, the American Association of Clinical Endocrinologists (AACE), the Obesity Society (TOS), and the ASMBS released updated guidelines for the perioperative care of the bariatric surgery patient that reduced the amount of total recommendations from 164 to 74 [33,145]. Their selection criteria include BMI greater than 40 if no comorbidities are present, greater than 35 if there is one or more obesity-associated comorbidity, or greater than 30 with diabetes or metabolic syndrome [145]. In addition, patients must have tried and failed non-surgical weight reduction and be willing and able to adhere to postoperative care. There also must be no current alcohol or drug abuse, no severe psychiatric illness that is uncontrolled, and no underlying disorder causing the obesity. Finally, patients must understand the risks, benefits, alternatives, necessary lifestyle changes, and expected outcomes. Since publication of these criteria, sufficient data were presented to the U.S. Food and Drug Administration (FDA) that led to the approval of more relaxed criteria (i.e., BMI less than 35 with an obesity-related comorbidity [mild obesity]) for LAGB. Researchers have demonstrated comparable safety and efficacy of LAGB between mildly obese and more severely obese patients [34; 145].

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    5 . Which of the following is NOT an advantage of LSG?
    A) Short hospital stay, averaging two days
    B) LSG does not require a foreign object in the body
    C) Produces more weight loss by re-routing the food stream
    D) Similar weight-loss maintenance rates as RYGB (approximately 50%)

    BARIATRIC SURGERY

    The increase in the number of LSG procedures reflects several advantages over other types of bariatric surgery. Initial excess weight loss is slightly less than RYGB (60% to 80% RYGB vs. >50% LSG); however, long-term weight maintenance rates are comparable at approximately 50% [166]. LSG requires no foreign objects in the body, as LAGB does, and does not re-route the food stream, as in RYGB. LSG hospitalization stays are shorter than other procedures, averaging two days [166].

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    6 . Approximately what proportion of patients who undergo RYGB develop dumping syndrome?
    A) 7%
    B) 30%
    C) 70%
    D) 100%

    BARIATRIC SURGERY

    Because RYGB alters the configuration of the digestive tract, it changes the body's response to certain foods. A "dumping syndrome" may occur, particularly with the ingestion of foods with high sugar content. Within a short time after eating, patients with dumping syndrome experience lightheadedness, palpitations, flushing, and diarrhea. Dumping syndrome occurs in 70% or more of gastric bypass patients initially [33,145]. In some, it resolves over time, but others have ongoing intolerance to certain foods. Some experts and patients feel that dumping syndrome is actually an advantage, because it discourages consumption of high-calorie, low-nutrient foods [166]. Reversal of RYGB has been proven as a safe and effective way to treat dumping syndrome [46,167].

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    7 . Which of the following is TRUE regarding perioperative mortality after bariatric surgery?
    A) Gastric bypass has lower mortality than LAGB.
    B) Mortality rates have remained the same over the past three decades.
    C) Mortality between 31 days and 2 years is essentially zero after gastric bypass.
    D) Mortality rates are generally lower in hospitals that do a high volume of bariatric surgeries than at those with lower numbers.

    COMPLICATIONS OF BARIATRIC SURGERY

    In 2007, Buchwald and colleagues conducted a meta-analysis of mortality data using studies published between 1990 and 2006 [67]. Based on a total of 361 studies including 478 treatment arms and 85,048 patients, they found an overall mortality rate of 0.28% within the first 30 days and 0.35% between 31 days and two years. For gastric bypass, 30-day mortality was 0.44% for open procedures and 0.16% for laparoscopic procedures. Mortality from 31 days to two years was 0.69% and 0.09%, respectively. For gastric banding, open procedures had a short-term mortality rate of 0.18%, while the short-term mortality for laparoscopic procedures was 0.06%. The longer-term mortality rates were statistically 0.00% for both groups. For the most part, this analysis found that mortality trended downward with more recent studies, and smaller studies had higher mortality rates than larger ones. Mortality was highest in observational studies (0.7%) compared with other study designs (0.07% to 0.30%) [67]. In addition, mortality among patients who have undergone LSG have shown to be similar to those of the more well-studied procedures, with a mortality rate ranging from 0% to 1.2% depending on study type [178]. Nguyen and colleagues conducted an audit of bariatric surgery cases at 29 institutions participating in the University HealthSystem Consortium Bariatric Surgery Benchmarking Project [30]. For each institution, 40 consecutive cases were examined; a total of 1,144 cases met inclusion criteria, which was age older than 17 years and younger than 65 years, BMI of 35–70, and no previous bariatric surgery. Procedures were primarily gastric bypass (91.7%), with smaller numbers of gastroplasty or gastric banding (8.2%) and BPD (0.1%). For gastric bypass, with about three-fourths of the procedures done laparoscopically, 30-day mortality was 0.4%. Restrictive procedures had a 30-day mortality of 0%, with 92% of procedures done laparoscopically. Data support the low incidence of severe adverse events and mortality.

    Other studies have shown that increased physician experience and higher case volumes are associated with lower mortality. For example, lower mortality rates have been reported at hospitals doing more than 100 bariatric surgeries annually compared with hospitals with lower numbers. Length of stay, morbidity, and costs were also lower at the high-volume institutions [68]. Concerns regarding the safety and uneven quality of bariatric surgeries performed across hospitals prompted the American College of Surgeons (ACS) and the ASMBS to implement an accreditation program for hospitals called "centers of excellence." The general guidelines to receive accreditation vary between programs but typically include a minimum volume of procedures, availability of resources for morbidly obese patients, and submission of outcomes data to a central registry [69,70]. The ASMBS and ACS also partnered with the Society for American Gastrointestinal and Endoscopic Surgeons to establish credentialing guidelines for bariatric surgeons to ensure that surgeons maintain a certain skill level and are prepared for potential complications during bariatric surgery [71].

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    8 . Cholelithiasis appears to be common after bariatric surgery. It is thought to be triggered by
    A) increased LDL.
    B) rapid weight loss.
    C) altered incretin signals.
    D) nutritional deficiencies.

    COMPLICATIONS OF BARIATRIC SURGERY

    Some adverse effects are not technically surgical complications, but occur as a result of rapid weight loss. Cholelithiasis is a common result of rapid weight loss and is frequently seen in bariatric surgery patients [60]. Estimates of symptomatic cholelithiasis after RYGB, for example, range from 3% to 28% in various studies [74].

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    9 . Although the opportune timing of pregnancy after surgery is unknown, the American College of Obstetrics and Gynecology recommends that women delay conception after bariatric surgery for at least
    A) 6 months.
    B) 12 to 24 months.
    C) 2 years.
    D) 5 years.

    CARING FOR PATIENTS AFTER BARIATRIC SURGERY

    The current recommendation from the American College of Obstetricians and Gynecologists (ACOG) is that women should delay pregnancy for 12 to 24 months after bariatric surgery to ensure that gestation does not occur during the rapid weight-loss phase [78,79]. However, the opportune timing of pregnancy after surgery is unknown. The ACOG also strongly recommends preconception assessment and counseling and education regarding possible complications. Prior to attempting pregnancy, obese patients should be encouraged to undertake a weight-reduction program that includes diet, exercise, and behavior modification. Evaluation for nutritional deficiencies and the need for vitamin supplementation are also recommended [80].

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    10 . Maximum weight loss after bariatric surgery generally occurs at
    A) 3 to 6 months.
    B) 6 to 9 months.
    C) 12 to 18 months.
    D) 18 to 24 months.

    WEIGHT LOSS AFTER BARIATRIC SURGERY

    Weight loss after bariatric surgery is usually most rapid in the first year. It may be fastest in the first few months, when caloric restriction is greatest. Weight loss is expected to slow at about six to nine months, and maximal total loss generally occurs at around 12 to 18 months [33].

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    11 . Approximately what percentage of patients with diabetes can be expected to have improvement or resolution of diabetes after bariatric surgery?
    A) Between 15% and 25%
    B) Between 21% and 50%
    C) Between 48% and 68%
    D) Between 69% and 100%

    EFFECTS ON OBESITY-RELATED CONDITIONS

    The AHRQ evidence report related that, in published bariatric surgery case series, diabetes improved or resolved in 69% to 100% of cases [23]. In the meta-analysis by Buchwald and colleagues, among studies that reported resolution of diabetes, 76.8% of patients had complete resolution [7]. In studies that also reported improvement, 86.0% had either resolution or improvement. A 2007 review found that diabetes resolved in more than 75% of bariatric surgery patients [9].

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    12 . A 2008 study comparing LAGB to lifestyle change (including the option of medication) showed that
    A) average weight loss with surgery and with lifestyle change were about the same.
    B) on average, the lifestyle change group gained weight, while the surgery group lost weight.
    C) the surgery group lost 62.5% of excess body weight and had 73% remission of type 2 diabetes.
    D) the lifestyle change group had about 22% excess weight loss and about 20% of patients had resolution of diabetes.

    EFFECTS ON OBESITY-RELATED CONDITIONS

    In 2008, researchers published data from a randomized controlled trial comparing lifestyle change, including the option of medication to treat obesity, to LAGB in patients with type 2 diabetes [101]. Out of 60 patients enrolled, 55 were followed to two years. Starting BMI was between 30 and 40, and diabetes diagnosis was recent, having been made within the past two years. The surgery group lost 62.5% of excess body weight, and 73% experienced remission of type 2 diabetes. In the non-surgical group, excess weight loss was 4.3% and diabetes remission was 13%. Remission of diabetes correlated with weight loss and also with lower hemoglobin A1c (HbA1c) levels at baseline. A study published in 2012 showed remission of type 2 diabetes in 62% of RYGB patients at a six-year follow-up [180].

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    13 . The primary mechanism for diabetes resolution with LAGB is thought to be
    A) loss of excess body weight.
    B) an increase in physical activity due to weight loss.
    C) alterations in incretin signals due to caloric restriction.
    D) changes in gut hormones due to the alteration in the anatomy of the small intestine.

    EFFECTS ON OBESITY-RELATED CONDITIONS

    While malabsorptive procedures may have additional mechanisms of action against diabetes, similar changes in gut hormones do not occur with purely restrictive procedures [111]. The reduction in diabetes associated with LAGB appears to be due to weight loss alone.

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    14 . After weight loss due to bariatric surgery, hypertension can be expected to
    A) be unaffected.
    B) decrease or resolve in many patients.
    C) resolve within a year in 94% of cases.
    D) increase due to better control of homeostasis.

    EFFECTS ON OBESITY-RELATED CONDITIONS

    Studies with this length of follow-up are uncommon, but some additional evidence is available on blood pressure several years after surgery. White and colleagues used data from a single surgeon's gastric bypass cases (variations on RYGB), collected over 14 years, to examine outcomes including the resolution of hypertension [112]. With a median follow-up of just over four years, 62% of previously hypertensive patients had normal blood pressure and 25% showed improvement.

    Shorter-term studies have also found resolution of hypertension to be common after bariatric surgery. Ahmed and colleagues conducted follow-up with 100 patients for one year after RYGB to evaluate changes in blood pressure [114]. By the end of one year, both the percentage of patients who were hypertensive and the number of patients taking medication for hypertension had decreased substantially. At baseline, 53 patients were on medication, with a decline to 15 at one year. Decreases in blood pressure occurred rapidly, beginning in the first week for some patients.

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    15 . According to the Swedish Obese Subjects (SOS) study, what was observed in patients with dyslipidemia following bariatric surgery?
    A) Recovery from low HDL was better in the controls than in the surgery group.
    B) Both HDL and LDL decreased at 2 years after surgery.
    C) There was no difference between surgery patients and controls in terms of recovery from hypercholesterolemia at 2 or 10 years.
    D) There was no difference between surgery patients and controls in terms of recovery from hypertriglyceridemia at 2 or 10 years.

    EFFECTS ON OBESITY-RELATED CONDITIONS

    Changes in lipids are also widely seen in follow-up studies of bariatric surgery patients, although long-term data are somewhat mixed [10]. In the SOS cohort, rates of recovery from hypertriglyceridemia and from low high-density lipoprotein (HDL) were better in surgery patients than in the control group at both two and 10 years of follow-up. Recovery from hypercholesterolemia, on the other hand, was not statistically different in surgical patients compared with controls at either time point. The incidence of hypercholesterolemia was similar as well.

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    16 . Which of the following is TRUE regarding long-term mortality following bariatric surgery?
    A) No studies have been completed with follow-up long enough to draw conclusions about mortality.
    B) Mortality after bariatric surgery is greater than that of obese patients who did not choose surgery, but quality of life is better.
    C) Compared with matched controls, bariatric surgery patients are less likely to die from diabetes but more likely to die from accidents or suicide.
    D) Compared with matched controls, bariatric surgery patients were less likely to die from diabetes but more likely to die from cardiovascular disease.

    EFFECTS ON OBESITY-RELATED CONDITIONS

    As discussed, in the short term there is a small but definite mortality risk associated with bariatric surgery. However, long-term mortality data suggest that, compared with obese controls, patients who choose surgery experience a reduced risk of premature death. Data from the SOS study show that, with an average of 10.9 years of follow-up, there were 129 deaths in the control group and 101 deaths in the surgery group. The unadjusted overall hazard ratio was 0.76 in the surgery group [129]. A review of data from the SOS study at 20 years follow-up found a long-term reduction in overall mortality as well as decreased incidences of diabetes, myocardial infarction, stroke, and cancer with bariatric surgery compared with usual care [84].

    Similar benefit was noted in a retrospective cohort study that compared mortality among 9,949 gastric bypass patients and 9,628 severely obese controls [130]. Matching for age, sex, and BMI was achieved in 7,925 of each group, and the mean follow-up was 7.1 years. Adjusted long-term mortality from any cause decreased by 40% in the surgery group compared with the controls, with 37.6 and 57.1 deaths, respectively, per 10,000 person-years. Cause-specific mortality in the surgery group decreased by 56% for coronary artery disease, by 92% for diabetes, and by 60% for cancer. Rates of death not caused by disease, such as accidents and suicide, were 58% higher in the surgery group than in the control group.

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    17 . Regarding nutritional deficiencies after bariatric surgery, which of the following is correct?
    A) Symptomatic thiamine deficiency occasionally occurs in bariatric surgery patients.
    B) Nutritional deficiencies can be expected to be similar after RYGB and LAGB.
    C) Nutritional deficiencies do not occur with purely restrictive procedures, and no supplements are needed.
    D) Vitamin D deficiency is rare after bariatric surgery because it is not preferentially absorbed in the duodenum and jejunum.

    LONG-TERM COMPLICATIONS

    Symptomatic thiamine deficiency after bariatric surgery is not usual, but cases of Wernicke-Korsakoff syndrome, a degenerative brain disorder, after both malabsorptive and restrictive procedures have appeared in the literature [135]. Patients who have unresolved nausea and vomiting may be particularly at risk. Case reports of beriberi have also been published, and the ASMBS guideline notes that occurrence may, in fact, not be rare [137,138]. Beriberi can cause irreversible neuromuscular disorders as well as defects in memory. Preoperative deficiency of thiamine has been estimated at <1% to 49% depending on time frame and type of weight-loss surgery [135].

    Vitamin D is absorbed in the ileum and jejunum, suggesting that deficiency of this nutrient would not be severe following RYGB. However, studies of vitamin D deficiency before and after bariatric surgery suggest that suboptimal levels of vitamin D are quite common preoperatively, making supplementation an issue. In a 2007 series of 95 patients, 54% were vitamin D deficient (<50 nmol/L) and another 34% had suboptimal levels (50–79 nmol/L) [139]. In another study, 80% of preoperative patients had 25-OH vitamin D (the storage form of the vitamin) levels less than 32 ng/mL [140]. The ASMBS estimates that as many as 90% of obese patients may have low levels of vitamin D preoperatively [135]. Although supplementation has been shown to increase levels following surgery, a pilot study involving 45 post-RYGB patients suggests that, for many patients, current levels of supplementation may not be high enough to normalize levels [141]. A 2017 study indicated that 96.2% of pre-procedure patients were deficient in vitamin D and, after four years, 86% still had a deficiency [64]. In addition, the ASMBS estimates that up to 100% of post-bariatric surgery patients have a vitamin D deficiency [135].

    Anatomical changes are likely not the only cause of nutritional deficiencies after bariatric surgery. The ASMBS guideline notes that purely restrictive surgeries, while once thought not to be associated with nutritional deficiencies, may in fact lead to deficiencies due to poor diet and food intolerance. Research on dietary habits after a restrictive procedure reinforces this concern, as demonstrated in a case study of consecutive patients in one surgical ward who had undergone VBG, a restrictive surgery, between 1986 and 1992 [143]. Sixty-two percent of eligible patients participated, and the average time of follow-up after surgery was 5.4 years. Patients' overall food intake had declined since before surgery, except for fluids, dairy products, and sweet foods. Fruit and vegetable consumption had declined the most, and then meat, fish, and complex carbohydrates. The authors of the study questioned whether the patients' relatively unhealthy diets might eventually counterbalance the benefits of weight loss.

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    18 . Which of the following is TRUE following RYGB?
    A) Constipation is a common complaint.
    B) Extended-release medications should generally be used instead of immediate-release formulations.
    C) Reduction in stomach acid due to structural changes may alter absorption of some medications.
    D) None of the above

    LONG-TERM COMPLICATIONS

    After RYGB, changes in the physical structure of the GI tract can influence the absorption of certain medications. Extended-release formulations that are designed to remain in the intestine for long periods may not be absorbed as well or according to the expected time course [134]. Immediate-release formulations are generally recommended in these patients; however, healthcare providers are not always aware of recommended vitamin regimens, dosages, and appropriate formulations. A retrospective study conducted from 2006 through 2007 in patients with a history of bariatric surgery examined vitamin/nutrient supplements and medication dosage formulations given upon admission. Daily multivitamin, calcium, iron, vitamin B12, and folic acid supplementation were evaluated. Of 133 patient admissions, 88% had a history of a malabsorptive procedure. Approximately 33% of patients were given a multivitamin; 5.1% were given supplemental vitamin B12; 7.7% received supplemental calcium; 11.1% received additional folic acid; and 12% received iron. Inappropriate formulations (e.g., non-immediate-release, enteric-coated) were ordered in 61.5% of patients. Fifty percent of patients were discharged with inappropriate formulations [146].

    Although medication absorption in bariatric surgery patients is not well studied, the reduction in acid due to structural changes in the stomach may alter absorption of medications that require an acidic environment. More pharmacokinetic clinical studies are needed to address the specific effects of various bariatric procedures on drug absorption [147].

    Beyond information about nutrition, day-to-day life after bariatric surgery is rarely addressed in the literature. To help illuminate patients' experiences following these procedures, Potoczna and colleagues reported on bowel habits after gastric banding, RYGB, and BPD [148]. Compared with before surgery, patients who had adjustable gastric banding were more likely to report increased constipation at three or more months after surgery. RYGB patients were more likely to report loose stools or diarrhea (46% after surgery, compared with 8% before). RYGB patients were also more likely to report malodorous flatus, to be bothered by it, and to feel that their social life was affected. A similar pattern was seen with BPD. For both RYGB and BPD, severity of flatus was inversely correlated with quality of life subscores on the bariatric analysis reporting outcome system scale.

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    19 . The U.S. Preventive Services Task Force (USPSTF) found fair to good evidence that intensive counseling about diet and/or exercise, with behavioral interventions, can help obese patients lose weight. Which of the following statements is correct?
    A) The USPSTF states that typical weight loss with the recommended strategies is about 3–5 kg.
    B) The Physical Activity Guidelines for Americans recommends 300 minutes of moderate-intensity aerobic activity per week.
    C) To meet current exercise recommendations, patients must do 30 consecutive minutes of moderate exercise 7 days per week.
    D) As a general rule, obese patients should be advised to reduce their caloric intake by 100 calories per day in order to lose 1 to 2 pounds per week.

    NON-SURGICAL WEIGHT-LOSS METHODS

    However, some patients will be able to lose weight and keep it off through increased physical activity and healthier eating. The U.S. Preventive Services Task Force (USPSTF) recommends intensive counseling and behavioral interventions to promote sustained weight loss for obese adults [149]. Counseling may address diet, exercise, or both, and behavioral interventions may be aimed at skill development, motivation, and support. The USPSTF concluded that these strategies could result in a typical weight loss of about 3–5 kg (6.6–11 lbs), lasting one year or more. Some patients will struggle to lose this amount of weight, while others will be able to lose substantially more.

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    20 . When pharmacotherapy is selected to help with weight loss,
    A) weight loss is typically about 15 kg per year.
    B) primary side effects are hypotension and dizziness.
    C) weight is often regained when the medication is stopped.
    D) weight loss typically approaches that seen with bariatric surgery.

    NON-SURGICAL WEIGHT-LOSS METHODS

    Some patients will benefit from pharmacotherapy to aid in weight loss. Approval criteria for anti-obesity drugs include a 5% or more mean placebo-subtracted weight loss after one year of therapy or a minimum of 35% of participants achieving more than 5% weight loss. The European Medicines Agency guideline requirements are similar. Both agencies also call for evidence of improvements in metabolic comorbidities [152]. At present, five weight-loss drugs are FDA-approved for long-term use: orlistat, lorcaserin, phentermine/topiramate, bupropion/naltrexone, and liraglutide [152,153,154]. Weight loss achieved through the use of medication tends to be modest, and weight is often regained when the drugs are stopped [155,156,157].

    Orlistat inhibits nutrient absorption. Orlistat has been shown to increase weight loss and improve cardiovascular risk factors. Primary side effects are gastrointestinal discomfort and a decrease in absorption of fat-soluble vitamins [152]. Independent reports of liver injuries (including six cases of liver failure between 1999 and 2008) prompted the FDA to approve a label revision for orlistat that includes a warning of possible severe liver injury [152]. However, the risk of severe liver injury is low, and this risk should be weighed against potential benefits [153]. Orlistat is indicated for the treatment of obesity in conjunction with a reduced-calorie diet [152].

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