Introduction

Bariatric surgery is a proven effective treatment for morbid obesity and its associated comorbidities, such as diabetes and hypertension. A multidisciplinary approach is essential to ensure maximum benefits that will last for the rest of the patient’s life and for prevention or treatment of complications. Besides the surgeon, the care team consists of the following providers: a primary care provider, a registered dietician, a clinical psychologist, and an exercise physiologist. Patients usually prepare for surgical treatment months before operation, assisted by a bariatric coordinator who helps guide them through the process. Data indicate that patients lose more excess weight and are less likely to regain weight when an intensive multidisciplinary approach is used [1]. This includes preoperative nutritional education and guidance with dieting and a regular exercise program [2–6]. Psychological assessment of mood, social and family support, substance use, cognitive function, psychosocial status, motivation, and willingness to undertake behavioral changes are crucial. An endocrinologist or internist with expertise in obesity treatment helps to optimize the patient for surgery by controlling comorbidities with medications and other therapies. In the postoperative period, continual follow-up with all members of the team significantly contributes to the enduring success of bariatric surgery. Multidisciplinary weight management is recommended by medical societies. The National Weight Control Registry has data showing narrow approaches to weight reduction are rarely effective but that a broad, multifaceted approach is more sustainable [7]. Furthermore, multidisciplinary weight management results in long-term maintenance of weight loss.

Role of the Surgeon

The bariatric surgeon performs an operation designed to aid with weight loss. Over several decades, different operations have been used to variably provide restrictive, malabsorptive, or behavioral strategies to affect weight loss. Currently, the predominant operations are Roux-en-Y gastric bypass and sleeve gastrectomy . These operations have similar short-term outcomes with regard to excess weight loss [8]. Therefore, the choice of operation is determined through a shared decision-making process between the patient, surgeon, and other providers of the multidisciplinary team. Roux-en-Y gastric bypass and sleeve gastrectomy provide similar results with regard to resolution of comorbidities such as diabetes within the first 5 years of surgery. However, further study is needed to determine if one operation is more effective in the long term [9]. Some data suggest that 10-year outcomes may be better with gastric bypass, but this operation has the potential for complications such as marginal ulcers and internal hernias [10].

The surgeon manages the patient in the immediate postoperative period. This includes monitored dietary advancement, pain control, and management of fluids. The surgeon is responsible for identification and treatment of postoperative complications, the most common of which include gastrointestinal leak, bleeding, and stricture. Roux-en-Y gastric bypass patients are at risk for developing marginal ulcers at the gastrojejunal anastomosis as well as internal hernias. Leaks are often not identified for days and as a result are often managed with percutaneous drainage. Strictures can be successfully treated with endoscopic dilation. Marginal ulcers are managed medically with acid suppression. Internal hernias may be life-threatening as a potential cause of bowel ischemia and require prompt operative intervention.

Although bariatric surgery allows for dramatic weight loss, there is overwhelming evidence supporting the need for intensive management of patients by a multidisciplinary team before and after operation. With the care and support of a full team, patients can expect better and more durable benefits to their health.

Role of the Specialist in Medical Management of Obesity

Primary care providers are on the front line in the fight against obesity and attendant comorbid conditions such as diabetes and hypertension. It is crucial for physicians to not only screen for obesity and diabetes but also to aggressively manage these conditions early in the course of disease. Appropriate patients should be referred to a Bariatric Center of Excellence , where intake begins with an internist or endocrinologist with expertise in management of obesity.

Optimization of prescribed medication may enhance the benefits of diet and exercise. Medications that are weight neutral or those that enhance weight loss such as metformin, DPP-4 inhibitors, α-glucosidase inhibitors, GLP-1 analogs, SGLT-2 inhibitors, and pramlintide should be prescribed over medications with a known side effect of weight gain. Furthermore, the use of FDA-approved anti-obesity medications such as lorcaserin, naltrexone with bupropion, topiramate with phentermine, and liraglutide is encouraged in certain patients with strong appetites. Patients on insulin may be switched to long-acting insulins like insulin detemir, insulin degludec, and insulin glargine U-300 in order to curb weight gain. Orlistat, a gastric and pancreatic lipase inhibitor, blocks dietary fat absorption by approximately 30%. Both randomized trials and meta-analyses have demonstrated that orlistat treatment can produce weight loss and reduce the incidence of type-2 diabetes in people with impaired glucose tolerance [11]. Several mechanisms have been proposed to account for the anti-diabetic effect of orlistat, such as improved insulin sensitivity, incomplete dietary fat digestion, partial stimulation of glucagon-like polypeptide 1 (GLP-1) release, and decreases in visceral adiposity. Phentermine-extended release with topiramate, lorcaserin, and naltrexone with bupropion are additional medications that can elicit weight loss through action on the central nervous system to reduce appetite. Clinical trials have shown these medications are effective at reducing HbA1c as well as lowering the progression to type-2 diabetes. Liraglutide , a GLP-1 receptor agonist that is approved for use in type-2 diabetes , has also been approved for weight loss [1].

The physicians who counsel patients on proper diet and exercise and who manage excess weight and its comorbidities are often the first to introduce the idea of surgical treatment to enhance excess weight loss. They have the opportunity to identify and refer appropriate surgical candidates. Ideal patients are those with BMI greater than 40 kg/m² or BMI greater than 35 kg/m² with associated comorbidities such as diabetes, hypertension, or sleep apnea, who are able to tolerate a general anesthetic and operation.

Prior to operative planning, selective referrals to additional specialists should be made at the discretion of the physician. Clinical suspicion for diseases such as obstructive sleep apnea, reflux, or heart disease warrants preoperative evaluation with the appropriate specialists. Further diagnostic testing helps determine whether a patient is appropriate for surgery or if there is room for further medical optimization in order to minimize the risks associated with surgery. In the case of gastroesophageal reflux, some evidence [12] suggests that a sleeve gastrectomy exacerbates the disease, and thus diagnostic testing may influence which operation is offered to patients.

Role of the Dietician

Although there is a genetic component of obesity, the substantial increased prevalence of the disease in recent years belies the major contributing factors of excess caloric intake combined with a sedentary lifestyle. The morbidly obese population typically subsists on high-fat, high-sugar foods with poor nutritional value. The causes of nutritional deficiencies in this population are multifactorial and include high intake of calorically dense foods with low nutritional quality, limited bioavailability of some nutrients such as Vitamin D , chronic inflammation status that affects iron metabolism, and small intestinal bacterial overgrowth which can lead to deficiencies in thiamin, vitamin B-12, and fat-soluble vitamins. The most common preoperative deficiencies found in studies include vitamin B-12 , iron, folic acid, vitamin, and thiamine [13–15].

Patients meet with a registered dietician upon presentation to the bariatric clinic. Evaluation includes review of dietary history and review of adherence to dietary recommendations during previous attempts of weight management. Potential barriers to following a nutrition plan are identified. Each participant should receive a hypocaloric meal plan rounded to the nearest 1200, 1500, or 1800 kilocalorie level for ease of application based on their gender, height, and previous energy intake.

Ideally, patients should begin following recommendations toward a postsurgical diet and make lifestyle modifications 6 months before operation. The overarching recommendation is a diet primarily low in fat and sugar and high in protein and vegetables without starch. Structured meal plans provide approximately 40–45% of daily energy intake from carbohydrates with 14 grams of fiber per 1000 calories, less than 35% from fat with less than 10% from saturated fat, and 1–1.5 g/kg of adjusted body weight from protein [15]. Protein intake is not calculated as a percentage of the total calories in order to avoid unintended reduction in absolute protein intake in a hypocaloric diet , which could accelerate lean muscle loss during weight reduction. Minimizing the loss of lean muscle mass is vital for long-term maintenance of overall weight loss. Patients are encouraged to maintain a food log, which is reviewed weekly by the dietician during the intensive phase of intervention to ensure adherence to the diet .

With most bariatric procedures , there is a restrictive component to intake to which the patient must adjust early in the postoperative period. Most surgeons also limit early diet to 2–3 ounces per hour of liquids to prevent staple line stress during healing. Still, the patient may experience nausea, vomiting, bloating, or epigastric pain. Following discharge, it is not uncommon for patients to develop such symptoms due to noncompliance with recommended dietary guidelines. Early re-involvement of the dietician after surgery , for ongoing education regarding food selections, timing, and volume of meals, is associated with significantly lower readmission rates [16].

Patient surveys indicate that therapeutic continuity is the most important element of follow-up care [17]. This is most often established with the bariatric dietician. Studies have demonstrated an association between the number of follow-up visits and weight loss post-gastric bypass surgery [16, 17]. Proper diet is helpful in reducing the incidence of slow weight loss, weight regain, weight plateauing, dehydration, discomfort, abdominal pain, indigestion, heartburn, and dumping syndrome after surgery, and patients rely on the dietician for guidance. Garg et al. [16] demonstrated that postoperative nutritional consultation resulted in significantly fewer readmissions due to dietary-related problems and more favorable 3-month change in serum thiamine, high-density lipoprotein, and triglycerides when seen by both surgeon and dietician versus surgeon alone. Attrition rates among bariatric patients range from 3 to 63% depending on the type of surgical procedure as well as the nature and frequency of prescribed follow-up care, and failure to return for follow-up visits is associated with more postoperative complications, lower percentage weight loss, a higher degree of nutritional deficiencies , poorer dietary compliance, and higher rates of surgery-related morbidity. It is estimated that 42% of patients will regain a large proportion of the weight initially lost and reenter the category of morbid obesity. The dietician helps to ensure the success of bariatric surgery by providing patients with practical nutrition knowledge as well as encouragement for physical activity and behavioral changes. Studies show that patients who are lost to follow-up have less success in weight reduction and maintenance and are at greater risk of developing nutritional deficiencies [18].

Vitamin supplementation becomes important due to decreased caloric intake and malabsorption following surgery. Multivitamin formulas should contain at least 45 mg iron, 400 mcg folic acid, and 8–11 mg of zinc. Supplementation with cobalamin (vitamin B12) in a 1000-mcg dose is recommended for all bariatric surgery patients. Daily supplementation of elemental calcium citrate with vitamin D3 is recommended. Patients are encouraged to take full supplements for at least 3 months after surgery, and the care team can then reevaluate at close intervals to best tailor supplementation .

Role of the Exercise Physiologist

Lack of physical activity in the preoperative period is a strong predictor of blunted weight loss following bariatric surgery [19]. In fact, cardiorespiratory fitness measured by oxygen delivery less than 15.8 ml/kg/min is associated with a longer operating time, intubation duration, and estimated blood loss during surgery, as well as more frequent complications including unstable angina, myocardial infarction, and deep vein thrombosis [11]. Exercise, before and after bariatric surgery, is an essential component of the multidisciplinary approach to weight loss. Ideally, an exercise physiologist meets with the patient early in the process and develops a personalized exercise plan based on the individual’s age, gender, health status, and exercise capacity. In clinical practice, exercise capacity may be tested by a simple method such as the 6-minute walk test. The common recommendation of 150 minutes per week of aerobic exercise or 10,000 steps per day improves fitness but is not enough for weight reduction or even for maintenance of weight loss. Effective exercise intervention for weight management should include a balanced mix of aerobic exercise to promote cardiovascular health, resistance exercise to maintain muscle mass, and flexibility (stretch) exercise to enhance functional capabilities and reduce risk of injury. Exercise plans may progress gradually over 3–6 months, from 20 minutes per day for 4 days each week to 60 minutes per day for 5–6 days each week. After completing the initial intensive phase, participants are usually encouraged to continue to exercise for 1 hour daily, 5–6 days per week, and to maintain greater than 300 minutes per week, with focus on resistance training to preserve muscle mass. This is important because diabetes worsens sarcopenia. The use of different exercise methods like circuit and interval training reduces boredom and increases duration of exercise. Exercise is particularly important after the intensive phase of weight management; it helps maintain the weight loss achieved during the intensive period.

Current recommendations to increase aerobic fitness in adults advise 150 minutes of moderate or 75 minutes of vigorous physical activity per week [1]. However, fewer than 10% of bariatric surgery candidates meet the activity recommendation prior to surgery and are most commonly categorized as having poor cardiorespiratory fitness. This low level of physical activity may explain why some individuals have an increased risk of composite surgical complications. Presurgical physical activity levels are positively associated with postsurgical physical activity and increasing physical activity levels prior to surgery may facilitate a beneficial increase in postsurgical exercise behavior. Preoperative exercise counseling combined with pedometry has been shown to increase 6-month postoperative physical activity levels to a greater extent than standard medical care alone [20]. Few data exist regarding the relationship between preoperative patient education and weight management programs on patient weight loss and postoperative outcomes after bariatric surgery. While some researchers have reported the positive impacts of these programs on postoperative weight loss, others, more often, have found undetectable differences. A recent retrospective analysis compared 56 patients who attended a preoperative weight management program to 441 surgical patients who did not attend such a program. The program consisted of lifestyle changes including monitored diet and exercise, as well as education and behavioral strategies. Subgroup analysis revealed a modestly higher excess weight loss at 12 months among Roux-en-Y gastric bypass who attended the weight management programs versus controls (66% compared to 56%) [21].

The Look AHEAD trial from 2014 provides the largest and longest randomized evaluation to date of an intensive lifestyle intervention for weight reduction [22]. The study was initially conceived to evaluate the effect on cardiovascular disease over time. Although the results show no difference between the compared group s for this primary endpoint, the study provides information about the feasibility of inducing and maintaining clinically significant weight loss, defined as a ≥5% reduction in initial body weight. Weight loss of this degree confers health benefits including prevention and resolution of type-2 diabetes, reduction in blood pressure and lipids, amelioration of nonalcoholic fatty liver disease, and improvements in urinary incontinence and sexual dysfunction. The intensive intervention arm emphasized lower caloric intake by restricting fat calories to less than 30% of total and also reducing low-quality carbohydrates such as sugar, sugar-flavored beverages , and high-calorie snacks. Increased exercise levels of 175 minutes per day at least 5 days per week were encouraged. This group had fewer hospitalizations, fewer medications, and lower health-care costs over a 10-year period, making the program cost-effective.

Two recent small randomized controlled trials indicate that physical activity interventions initiated postoperatively can also increase patients’ activity levels and contribute to improved surgical outcomes, including weight loss, body composition, and fitness [21]. There is also evidence to suggest that increasing physical activity preoperatively may reduce surgical complications and there is substantial support showing that consistent activity is the most important predictor of long-term weight loss maintenance [23].

Clinicians report that doubt of counseling efficacy and lack of patient interest are barriers to providing exercise counseling in clinical care. These barriers may, in part, be responsible for recent survey results which revealed that only 22% of patients of bariatric surgical centers accredited by the American College of Surgeons Bariatric Surgery Center Network report having received postoperative exercise consultation, despite accreditation requirements to establish procedures for exercise counseling [21]. However, evidence that motivated patients can increase their activity level and obtain the attendant health benefits, if given very clear guidelines and assistance in reaching goals, justifies regular exercise programs in the clinical care of bariatric surgery patients. Clinicians can do their part to increase the exercise level of patients during all phases of their care, including providing referrals for exercise testing, physical therapy, and an exercise specialist as indicated.

Role of the Mental Health Professional

Preoperative psychological assessment of the bariatric patient is an essential component of ensuring optimal outcomes. Morbid obesity is commonly associated with depression and low self-esteem. The social stigma and poor body image associated with obesity contribute to psychopathology. Oftentimes binge eating is the result of poor impulse control, depression, emotionality, or self-consolation. Psychiatric diseases such as depression and bipolar disorder are associated with less excess weight loss and weight regain in the postoperative population. The preoperative psychological evaluation aids in identification of patients who are capable of adherence to diet and exercise regimens in the long term. It also helps to identify risk factors such as depression, which can be treated with medication and psychotherapy in order to improve weight-loss outcomes. Overeating and binge eating become such an ingrained part of these patients’ lives, often serving as a coping mechanism. The psychological component of pathologic eating behavior must be addressed in these patients because once they undergo bariatric surgery, they lose this coping mechanism. This can lead to depression which negatively impacts postoperative weight loss [24].

The primary objective for the psychosocial evaluation is to provide screening and identification of risk factors or potential postoperative challenges that may contribute to a poor postoperative outcomes [25–30]. Patients with such factors benefit from additional management or intervention before and/or after surgery. In some cases, these issues may contraindicate surgery altogether. Another important function that the preoperative psychosocial evaluation process serves is to establish a positive and trusting working relationship between the behavioral health clinician and the patient. When the clinician presents as a support who will help the patient proceed to surgery and ensure the best possible outcomes, the patient’s willingness to be open and candid during the evaluation increases. Establishment of trust and rapport during the initial evaluation also serves to enhance the patient’s willingness to seek behavioral support after surgery if problems are encountered. Even a patient with excellent postsurgical weight loss may encounter psychosocial difficulties and challenges after surgery, ranging from disruptions in interpersonal relationships and body image dissatisfaction to concerns as serious as substance abuse and even suicidal behavior. The preoperative psychological assessment helps not only with the outcome measure of weight loss but also measures of metabolic status and medical comorbidities, quality of life, and psychosocial and behavioral functioning.

The initial clinic visit consists of a clinical interview, which includes routine general mental health intake assessment of psychopathology and mental status. Patients with severe obesity, and particularly the ones seeking surgical weight loss treatment, are more likely to report current or lifetime mood and anxiety disorders. Post-traumatic stress disorder, social phobia, and panic disorder are common. This visit also clarifies weight history, including weight trajectory over time and past weight-loss attempts. This history helps to identify important environmental and physiologic contributors that have affected the patient’s weight. It also allows the evaluator to obtain information about the specific types of weight-loss interventions that have been tried, duration of adherence to the various approaches, and what factors have been helpful in promoting adherence or barriers to sustained behavior change. Developmental and family history, cognition, personality traits and temperament, substance abuse, expectations following surgery, social support, and motivation are all important factors to assess during the interview as they may impact the success of surgery.

Recent literature has consistently demonstrated that personality traits and temperament have an influence on postoperative outcomes. In particular, low conscientiousness, poor impulse control, and elevated neuroticism are related to risk for obesity as well as suboptimal outcomes following bariatric surgery. The trait of persistence, or an ability to continue to pursue one’s goals despite immediate setbacks and frustration, is a significant predictor of weight loss after surgery [24].

Following the preoperative psychological assessment, a report is completed which includes recommendations based on the findings of the evaluation. These may include interventions designed to minimize barriers to optimal psychosocial and medical outcomes after surgery. For example, after noting that the patient has depression, the evaluator will recommend specific methods to ensure that the patient’s mood symptoms do not interfere with postsurgical self-care and behavioral adherence or pose a risk for self-harm. The aim of the presurgical evaluation should be to assess the impact that such psychological symptoms or diagnoses would have on postsurgical adherence and self-care. The focus of the assessment is on the extent to which daily functioning is affected, how stable the patient has been and for how long, whether appropriate psychological treatment is in place , and how well any symptoms are being managed at the time of presentation.

Some evidence suggest that postoperative psychological support services also impact outcomes. Existing postsurgical psychological services are characterized by a large variation across bariatric programs, ranging from individual psychotherapy and group therapy to support groups. Recent systematic review with meta-analysis of nine studies looking at the effects of postsurgical psychological services indicate a relatively modest effect on weight loss up to 3 years following bariatric surgery [31]. However, a randomized controlled trial involving 145 patients published in 2015 concluded that psychological support pre- and post-bariatric surgery had no impact on weight loss as measured by BMI and change in BMI after a year [32]. The authors argue that psychological support should be targeted to patients who start to demonstrate weight regain following surgery. Further study with methodological rigor is needed in order to elucidate the role of postoperative psychological services.

Analysis of postsurgical psychosocial factors indicates that the pathologic behaviors of binge eating and grazing, as well as presence of depressive disorders, negatively impact weight-loss outcomes. Conversely, adherence to dietary and physical activity guidelines positively predict weight loss. Postoperative identification of disordered eating and depressive disorder provides an opportunity for targeted behavioral and medical interventions, which may help to attain better long-term weight loss outcomes.

Weight Regain

Among patients who experience weight regain, the return of hunger or food cravings may lead to maladaptive eating behaviors in response to internal and external cues. Acceptance-based behavioral treatments specifically target the psychological challenges patients face by providing them with skills to handle undesirable psychological experiences in the service of core long-term values. Acceptance and commitment therapy directly address the causes of postoperative weight regain by helping patients to make mindful decisions based on their weight-control goals despite the internal states that make doing so challenging. For example, patients learn tools to gain psychological distance from thoughts and emotions, allowing them to act independently of these internal experiences. These kinds of behavioral treatments are especially effective for individuals with greater disinhibition and responsivity to food.

Weight regain is a substantial challenge for patients and providers following bariatric surgery. Understanding risk factors helps prevent or reduce the adverse influence on weight-loss outcomes. Preoperative age, sex, race, body mass index, and diabetes status are reported determinants associated with nonresponsiveness to surgery [11]. Elderly patients exhibit sarcopenia and insulin resistance to a greater degree than younger patients, both of which promote fat storage. Women may have a blunted response in comparison to men due to sex hormones; high testosterone in women increases diabetes risk, and women have relative leptin resistance which may increase caloric intake. Women also have elevated ghrelin levels, resulting in higher total fat mass. Latino and black patients tend to lose less weight; whether this is the result of genetic predisposition, culture, or socioeconomic status remains unclear.

Insulin-resistant diabetes plays a major role in fat distribution and thus excess weight. Excess fatty tissue and diabetes are intricately related and create a vicious cycle. Increased white adipose tissue in the abdominal visceral region increases the expression of macrophages and inflammatory cytokines including TNF-α and interleukin-6 that, in turn, leads to elevated systemic inflammation. This chronic inflammatory state contributes to insulin resistance. Moreover, increased inflammation in adipose tissue downregulates adiponectin, which exacerbates systemic insulin responsiveness in tissues including the skeletal muscle and liver. This is problematic as insulin resistance promotes β-cell dysfunction, endothelial dysfunction, hyperglycemia, and increased risk of cardiovascular disease.

The development of social media platforms has led to the formation of patient-led discussion groups, which provide information related to bariatric surgery and support to members. The role of social media in health care is in evolution, and it is important for providers to be familiar with its impact on patients because its powerful influence. The quality and veracity of information presented to potential surgical candidates as well as those who have undergone weight loss surgery are questionable and can confuse or mislead members if the information is contradictory to that which is provided in clinical settings. It stands to reason that the management of social media groups and the information and support they provide should fall to the health-care providers for this population. It remains unclear what influence social media has on surgical outcomes, but it will be important for clinicians to be aware of its presence, to get involved, and monitor its long-term effects.

Conclusions

A multidisciplinary approach to the bariatric patient clearly leads to better and more sustainable weight-loss results. Bariatric operations are not “quick fixes” to obesity; rather, they comprise one integral element which acts synergistically with those of diet , exercise, medical management, and cognitive–behavioral therapy to provide the best outcomes. Future studies of this population are required in order to more fully understand how these elements determine outcomes. For instance, it remains to be seen how the timing and content of exercise regimens impact the amount of excess weight loss and the sustainability of those results. Frequency and method of psychological counseling may positively affect results, but this requires further examination. Closer follow-up with a bariatric dietician and primary care physician may also play a role, although this remains to be fully characterized. More intensive lifestyle interventions and involvement in support groups have the potential for positive influence, but these need to be more clearly defined and standardized in order to measure their effects. Information obtained directly from patients suggests the importance of support systems before and after surgery; many report that peer, dietetic, and psychological support positively influence weight loss outcomes in the long term [33]. As more high-quality studies are produced and long-term data become available, the multidisciplinary team is best positioned to deliver what is needed for patients to have the best possible outcomes.