As Family Nurse Practitioners (FNPs) increasingly find themselves managing patients with morbid obesity and their comorbidities, evidence-based practice (EBP) provides a wealth of information to help guide the FNP and their patients to make informed decisions regarding treatment options and their outcomes. EBP has become an expectation for the profession of Nursing, especially when considering the role of the Advanced Practice Nurse (APN). EBP been defined as the constant use of current best evidence when making patient decisions, combined with clinical judgment and patient preferences (Polit & Beck, 2017). The Iowa Model of Evidence-Based Practice to Promote Quality Care was used to develop the following PICOT question: do obese patients who undergo bariatric surgery sustain more weight loss one year after their procedure as opposed to obese patients who use traditional diet and exercise methods for weight loss? By using the Iowa Model, this author identified the growing problem of obesity in our society, as one-third of Americans are considered obese (Choudhury et al., 2014). Bariatric surgery has become an increasingly popular option for obese patients for weight loss. Moving through the Iowa Model this author asked is there enough evidence supporting invasive procedures like bariatric surgery for sustained weight loss, or should more emphasis be placed on lifestyle changes to achieve a healthy weight status. Significance to NursingObesity is associated with multiple comorbidities, including heart disease, metabolic disorders, hyperlipidemia, and hypertension (Grayson et al., 2014). In 2015-2016 obesity (body mass index > 40) affected approximately 93.3 million adults in the United States, contributing to some of the most leading causes of preventable death like certain cancers, stroke, type 2 diabetes and heart disease (Centers for Disease Control and Prevention [CDC], 2018). Estimated medical costs for those who were considered obese were $1,429 higher than those of healthy weight (CDC, 2018). As rates of obesity continue to rise in the U.S, increasing the cost of health care and the morbidity and mortality of its citizens, Advanced Nurse Practitioners must evaluate and understand the physiologic mechanisms of weight loss as well as the ability to keep their patient’s weight stable following significant weight loss. Evidence-Based ResearchObesity is a growing problem in American society and is associated with multiple comorbidities. Numerous studies have explored the effects of diet and exercise for weight management, but it is now common for obese patients to undergo bariatric surgeries such as Roux-en-Y gastric bypass (RYGB) or gastric band surgeries to achieve weight reduction. Sustaining significant weight loss through medical management/diet and exercise or surgical strategies has proven to be difficult for both groups, but studies have shown that surgical patients may be more successful. Body Mass Index (BMI) is one of the leading indicators determining which patients will qualify for bariatric surgery. Choudhury et al. (2014) report that current NIH guidelines indicate that patients who have failed medical intervention/diet and exercise strategies for weight loss and who have a BMI of > 40 or > 35 kg/m2 with significant comorbidities are eligible for RYGB. A policy statement made by the American Society for Metabolic and Bariatric Surgery (ASMBS) proposes that this range is too restrictive and prevents patient who has a BMI of > 30 to > 34.9 kg/m2 (class I obesity) from receiving benefits from bariatric surgery (Choudhury et al., 2014). Using a body mass index (BMI) threshold of 30-45 kg/m2, Cummings et al. (2016) conducted a study comparing RYGB and intensive lifestyle changes and medical intervention (ILMI) for type II diabetes. Based on the survey results of 1,808 adults ages 25-64 with type II diabetes, this random control trial (RCT) assigned 43 qualifying participants to a 1:1 ratio RYGB vs. ILMI (Cummings et al., 2016). They found that diabetic patients who had undergone the RYGB procedure had better remission of type II diabetes compared to those who receive ILMI one-year post-study (Cummings et al., 2016). The above study is supportive of the position taken by Choudhury et al. (2014) that lowering the BMI ceiling to below the currently established 35-40 kg/m2 would be beneficial to an expanded patient population. Using a Markov-based decision-analytic model, researchers evaluated the impact of RYGB vs. diet and exercise on the life expectancy of obese patients (Choudhury et al., 2014). They found that patients with a BMI of 31.3 kg/m2 had improved average life expectancy of 3.4 years with RYGB intervention (Choudhury et al., 2014). Bariatric surgery aids in excessive weight loss in morbidly obese patients and may be contributory in sustaining weight loss for years to come. Several studies have found that regardless of procedure, weight loss is more significant in surgical cases than strict diet and exercise. Patients who underwent the Primary Obesity Surgery Endoluminal (POSE) procedure were studied in an RCT conducted by Miller, Turro, Greve, Bakker, Buchwald, and Espinos (2017). POSE is a bariatric procedure where full-thickness gastric tissue plications are inserted in the fundus and distal body of the stomach to provide the patient with early and prolonged feelings of fullness (Miller et al., 2017). Participants in the experimental group experienced significant weight loss of 45% opposed to the 18.1% seen in the diet and exercise (control) group at 12 months post-procedure (Miller et al., 2017). Researchers found that shortened time to satiety experienced by the POSE procedure patients was an essential factor in percent of total body weight loss one year after their procedure. No such correlation was found in the diet and exercise group (Miller et al., 2017). When looking at RYGB procedures, similar results are found. It is believed that weight loss is related to a reduction in energy intake. The quantity of food intake and not so much the quality of food eaten had a more significant impact on weight loss over the first-year post-procedure, especially for those with more weight to lose (Bobboni-Harsch et al., 2002). Preprocedural body weight may have a significant role since energy requirements are higher for those with more massive degrees of obesity making energy deficits more evident (Bobboni-Harsch et al., 2002). Analysis between bariatric surgery patients and those adhering to strict diet and exercise indicates that the combination of baseline waist circumference (WC) and rate of weight loss (RWL) was a significant predictor of percent of weight reduction at one year in the bariatric surgery group (Kulovitz, Kolkmeyer, Conn, Cohen, & Ferraro, 2014). The results suggest that bariatric surgery patients who are losing weight at a slower rate and have a larger WC at baseline tend to lose more weight over one year (Kulovitz et al., 2014). Body composition and type of adipose tissue lost was also evaluated through several studies. Preserving lean body mass in the presence of rapid weight loss is essential for any weight loss population. Kulovitz et al. (2014) evaluated body composition and weight maintenance after a 15% reduction in body weight in medical weigh loss vs. bariatric surgery. The study matched patients with a BMI of 46.6 + 6.5kg/m2 who underwent laparoscopic bariatric surgery (LBS) with 24 patients involved in combined medical and behavioral treatment. Both groups were evaluated on BMI, WC, body weight, and body composition at baseline and after 15% weight loss. Results showed a 3:1 ratio of percent fat mass loss to percent lean body mass loss in both medically treated patients and LBS patients (Kulovitz et al., 2014). However, the goal of 15% weight loss was achieved more rapidly in the LBS group with ability to maintain or continue weight loss through the next year (Kulovitz et al., 2014). Visceral adipose tissue is thought to contribute to metabolic disease and cardiovascular disease more significantly than BMI. Bariatric surgery patients have been found to lose more visceral abdominal and cardiac adipose tissue when compared to patients who received traditional diet and exercise weight management (Wu et al., 2016). In contrast, Merlotti, Ceriani, Morabito, and Pontiroli (2017) found that neither bariatric surgery, nor weight loss promoting drugs, or diet and exercise targets visceral fat, but that visceral fat loss is linked to subcutaneous fat loss. However, bariatric patients in this meta-analysis did have more significant changes in BMI, waist circumference, subcutaneous adipose tissue and visceral adipose tissue than patients receiving diet medications or the diet and exercise group (Merlotti et al., 2017). Research in this paper was conducted using the Evidence Hierarchy to determine the best evidence. Randomized controlled trials (RCT) are near the top of the evidence hierarchies providing strong evidence on the effectiveness of therapies (Polit & Beck, 2017). Many of the studies reported were RCT. However, one expert opinion did bring up the difficulty in a study involving a surgical procedure being a purely RCT. Sugarman and Karl (2005) suggest RCT studies are not a suitable standard of evidence for surgical procedures stating that a surgical procedure is never blinded, and a placebo would be unethical. Surgical procedures must rely on observational, cohort studies (level IV), or standards of practice that have empirically been proven safe and advantageous (Sugerman & Kral, 2005). While these authors make a valid point this type of expert opinion is a level VIII on the Evidence Hierarchy making it the least reliable evidence. DiscussionResearch indicates that bariatric surgery patients are more successful at sustaining significant weight loss one year after their procedures than patients who engage in traditional diet and exercise methods. The studies conducted in this literature review were at the top of the Evidence Hierarchy. These studies placed at levels I-IV and supported the conclusion that bariatric surgery is beneficial for obese patients to accelerate and maintain excess weight loss. By achieving substantial weight reduction, these patients significantly reduced their obesity-related comorbidities. While bariatric surgery is the most effective way for morbidly obese patients to achieve significant weight loss, many of the studies researched for this paper found that bariatric surgery alone was not a predictor of long-term significant weight loss. Patient behavior changes have considerable effect on post-procedural outcomes. Patients who have bariatric procedures but continue with unhealthy habits like lack of physical activity, consuming high calorie, nutrient-deficient foods, grazing, and snaking had poorer outcomes following bariatric surgery (Mundi, Lorentz, Swain, Grothe, & Collazo-Clavell, 2013).Welch et al., (2011), found that patients who had laparoscopic gastric bypass (LGB) experienced and 59.1% excess weight loss at 2.5 years post-procedure. After considering other psychosocial and physiological factors the study concluded that aerobic exercise was more impactful on percent of excess weight loss than diet, fluid intake, or attendance at clinic visits or support groups (Welch et al., 2011). Likewise, Ren, Lu, Zhang, and Xu (2018) found in their meta-analysis that patients who engaged in physical activity after bariatric surgery experienced an extra mean value of 1.94kg of weight loss compared to those who underwent surgery alone. This suggests that while evidence-based studies show bariatric surgery as a viable option for obese patients to lose weight, clinicians caring for these patients should continue to encourage behavior changes and promote physical exercise. Understanding that behavior changes such as physical activity may prove to be challenging for many of these patients will guide providers in managing their own, as well as their patient’s expectations of post-procedure abilities.Many patients underestimate their post-surgical abilities for physical exercise and become frustrated with the process (Peacock, Sloan, & Cripps, 2014). Ren et al. (2018) found that patients who waited at least one year after their bariatric procedure were more successful at their physical exercise attempts. They attributed this to patients adapting to the physiological changes associated with their surgery, which motivated behavioral changes increasing weight loss (Ren et al., 2018). Providers who take this into account may adjust their expectations and the timing of introducing physical activity to post-surgical patients. Conclusion Obesity is a rapidly growing epidemic in the U.S., expanding health comorbidities for patients and increasing their health care costs. Bariatric surgery has become a popular and effective way for these patients to achieve and maintain considerable weight loss. However, health care providers should not ignore the necessity for behavioral changes for obese patients to continue their weight loss journey. Understanding the barriers faced by post-surgical patients will help guide FNPs in developing not only their expectations but also the patient’s expectations in achieving a healthier lifestyle.