Predicting Factors for Weight Regain after Bariatric Surgery

Abstract

Weight regain (WR) after bariatric surgery (BS) is emerging as a common clinical problem due to the increase in the number of procedures performed worldwide. Weight regain is defined as regain of weight that occurs few years after the bariatric procedure and successful achievement of the initial weight loss. Causes of WR following BS are multifactorial and can be categorized into two main groups: patient and surgical-specific causes. Several mechanisms contribute to WR following BS. These include hormonal mechanisms, nutritional non-adherence, physical inactivity, mental health causes, maladaptive eating, surgical techniques, and the selection criteria for the weight loss procedure. Higher preoperative BMI seems to be associated with WR and worse weight loss results in a long term. Patients with baseline BMI ≥ 50 kg/m2 are more likely to have significant WR, while those with BMI < 50 are likely to continue losing weight at 12 months post-surgery. The aim of the chapter is to discuss and reveal all main factors, which may contribute to weight regain after bariatric surgery and emphasize how multifactorial assessment and long-term support/follow-up of patients by key medical professionals can diminish the side effects of weight regain.

1. Introduction

There are several definitions of Obesity worldwide [1]. Interestingly, it is considered as a kind of malnutrition nowadays. Morbid Obesity is mostly a problem in high-income countries, according to statistical data with prevalence of countries in North America. However, overweight and obesity are a socially significant growing problem in low- and middle-income countries also. The estimated increase of Obesity among children is more than 30% higher in those countries than in developed countries in the last 10 years. The data confirm that 1.9 billion adults worldwide were overweight in 2016, with 650 million being Obese. People who are obese have much higher risks of many serious health problems than nonobese people [2, 3]. Obesity affects every system of the body. The results of outcome of bariatric surgery (BS) confirm the positive effects of surgery over such conditions as Diabetes type 2 (DT2), fatty liver disease, cancer. There is evidence for improvement of thyroid function, heart function, fertility, and sexual function in patients who have had weight loss surgery. More than 50 bariatric procedures have been proposed and implemented so far. As a result of time and trial, several procedures have been established as standards. The final goal of those procedures is for the Morbid Obese patient to achieve at least a loss of 50–70% of excess weight [EWL] or about 20–30% loss of his initial weight. Some authors consider a successful outcome, when achieving a Body Mass Index [BMI] < 35 kg/m² 2 years after surgery in those patients. However, the BMI as a criterion for a successful outcome after B/M surgery is under debate due to several reports that even patients with BMI of 32.0 can benefit from Metabolic surgery. So, we think that the quality benchmark for outcome of any M/B surgical procedure should be a combination of percentage of EWL in short and mid-term, extrapolated with percentage of WR in a long term—about 10 years after surgery. We support the suggestion of SOS study [4, 5] that patients should not regain more than 20–25% of their lost weight within 10 years after the primary procedure. Several studies confirm average weight regain of 12% of total body weight in patients who underwent Roux en Y Gastric bypass (RYGB), while those reported for Sleeve Gastrectomy (SG) were variable, ranging from 6% at as early as 2 years post-surgery to 76% at 6 years post-surgery [6, 7, 8]. Morbid Obesity, like other chronic diseases, persists for prolonged durations and requires a continuous close follow-up to reassess the efficacy of treatments, including Bariatric/Metabolic surgery. Most of the reports for very good and excellent results after weight loss surgery [WLS] are short or mid-long term up to 5 years’ studies. Unfortunately, the studies, reporting results for more than 5 years after surgery, revealed a significant rate of WR in patients with Body Mass Index over 50 or history of comorbidity of more than 5 years [6, 9].

2. Definition of weight regain

The general metrics to assess the success of the surgeries includes calculating % of excessive weight loss (EWL) (>50%), % of total weight loss (TWL), and % of weight regain (WR) post-surgery. Different studies have shown a large amount of variability within these values, which have been attributed to the type of surgery, the preoperative BMI, and to the race and ethnicity that the patients belong to [2, 3, 4, 10]. Literature review studies have revealed that only a limited number of them have looked at differences in weight loss patterns across different populations and specifically in the European population, where Bariatric/Metabolic procedures are performed routinely in nowadays. However, the sustained health improvements following bariatric surgery are dependent on the individual’s adherence to long-term changes in lifestyle habits [11, 12]. As a result, despite its effectiveness, weight regain after bariatric surgery is a persistent problematic issue!

The first group of patients are those who do not lose the expected or anticipated average percentage of weight following surgery, while the second group are patients who lose a successful amount of weight after Bariatric/Metabolic Surgery (B/MS), but they regain some or most of the weight 5 or more years after the initial procedure [10].

According to several authors and publications about weight loss surgery, we must make a distinction between two types of WL failure post (B/MS). The first is known as insufficient WL (IWL). The second is known as weight regain (WR). IWL is defined as excess weight loss (EWL%) of <50% at 18 months after BS. Weight regain is defined as regain of weight that occurs few years after the Bariatric procedure and successful achievement of the initial weight loss. Literature review found several definitions for WR [13, 14, 15] as:

• regaining weight reaching a body mass index (BMI) >35 after successful WL;

• an increase in BMI of ≥5 kg/m² above the nadir weight; >

• 25% EWL% regain from nadir; increase in weight of >10 kg from nadir;

• any WR or any WR after Diabetes Mellitus type 2 (DT2) remission;

• an increase of >15% of total body weight from nadir.

All those definitions describe one and the same problem: WR several years after B/MS. A robust review of the main causes, leading to that problem, is mandatory in order to answer to significant health and social issues about application of B/MS worldwide.

3. Factors for weight regain after bariatric surgery

It is difficult to outline current factors, leading to WR after B/MS. The role of those factors and their influence on patient’s behavior, eating habits, and ability to keep his weight under control after the primary procedure are not well understood or investigated robustly. However, most of the published reviews confirm that they have been attributed to several surgical, biological, and behavioral factors [2, 16]. We can identify two groups of factors nowadays. The first group is of so-called non- modifiable factors as hormonal, metabolic, surgery-related [14, 17]. The second group is of so-called “modifiable behaviors,” where patients should receive more support and care within 5 years after surgery by healthcare professionals. WR remains a major challenge in relation to the long-term success of B/MS [7, 8]. Although weight regain is a consistent finding among studies, there are considerable variations in the magnitude and rate of weight regain depending on factors ranging from behavioral, dietary, lifestyle, psychological, ethnic, and racial differences. Interestingly, there are studies that report an average of 56% WR weight within 10 years after primary surgery [10, 18]. A poor prognostic indicator for WR after B/MS is the slow weight loss in the first two postoperative years. Medical based evidence confirms that patients, who achieve 20–30% of total weight loss at one to 2 years postoperatively, can regain an average of 7% of their total body weight from their lowest postoperative weight over the course of 10 years [6, 7, 9, 19, 20]. According to those studies, the estimated average WR is about 15% (between 2 and 5% of weight from their lowest reported postoperative nadir weight) within 2 years after Roux en Y Gastric bypass. Those studies have reported an increase to 70% of patients between 2 and 5 years after Sleeve Gastrectomy, and 85% increase of WR at over 5 years post-surgery [10, 21] after that procedure. The high prevalence of weight regain after B/MS has resulted in a significant increase in revisional bariatric surgery [2, 6], which is a cause for increase in surgical risk and adverse outcomes to the patient [22, 23]. Causes of WR following B/MS are multifactorial and can be categorized into patient and surgical-specific causes. The summary of all aforementioned factors could outline the importance of following about weight regain:

1. Gastrointestinal, hormonal, and genetics factors

2. Gender, ethnic, and racial factors

3. Behavioral, dietary, lifestyle, and psychological factors

4. Performed Weight loss procedure as a technique and individual needs of the patient.

4. Gastrointestinal, hormonal, and Genetics factors for weight regain

There are known more than 30 gut hormone genes expressed and more than 100 bioactive peptides distributed in the gastrointestinal tract, which makes it the largest endocrine organ in the body [15, 17]. Several hormones in Gastrointestinal tract, which contribute to increase or decrease of food intake and in experimental studies, are directly associated with nutrition and body weight. That is the family of so-called PP-Fold Proteins. They consist of neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP). PYY and PP are secreted from gastrointestinal tract, whereas NPY is predominantly distributed within central nervous system [23]. Circulating PYY concentrations are low in fasted state and rise rapidly following a meal with a peak at 1–2 hours and remain elevated for several hours [24]. In both lean and obese humans, intravenous injection of PYY reduces appetite and food intake, suggesting that, unlike leptin, the sensitivity of PYY is preserved in obese subjects. Pancreatic Polypeptide (PP). PP is secreted from PP cells in the pancreatic islets of Langerhans. The anorectic effects of PP have been demonstrated in several experimental models. In leptin-deficient mice, repeated intraperitoneal injection of PP decreases body weight gain and ameliorates insulin resistance and hyperlipidemia [15]. GLP-1R is widely distributed particularly in the brain, GI tract, and pancreas [10]. It is known from experimental studies that circulating GLP-1 levels rise after a meal and fall in the fasted state. GLP-1 is associated with reduced food intake, and it can suppress glucagon secretion, leading to delayed gastric emptying [21]. Clinical trials in normal weight and obese subjects have also shown a reduction of food intake after a dose-dependent intravenous infusion of GLP-1. It is also known that Morbid obese patients have a blunted postprandial GLP-1 response compared to normal weight patients. GLP-1 is investigated about its potent incretin effect in addition to its anorectic action. That means that it can stimulate insulin secretion in a glucose-dependent manner following ingestion of carbohydrate. Experimental studies about application of Ozempic in clinical practice have confirmed positive effect of continuous subcutaneous infusion of GLP-1 to patients with type 2 diabetes for 6 weeks. GLP-1 infusion reduces appetite, body weight and improves glycemic control [25]. Research studies about the effect of Ozempic and Trulicity as Once-weekly subcutaneous injection have demonstrated greater improvements in glycemic control and weight loss in patients with Diabetes type 2 (DT2) and Obesity. On the other hand, Ghrelin is the only known orexigenic gut hormone involved in the mechanism of Morbid Obesity. Levels of circulating ghrelin increase before meal and fall rapidly in after meal period [25]. Fasting plasma levels of ghrelin are high in patients with anorexia nervosa [21] and in subjects with diet-induced weight loss. By contrast, obese patients have a less marked drop in plasma ghrelin after meal injection [25]. Dysregulation of ghrelin secretion is also implicated in the mechanism through which sleep disturbance contributes to Obesity. Subjects with short sleep duration have elevated ghrelin levels, reduced leptin, and high Body Mass Index (BMI) compared with patients with normal BMI and normal sleep duration [21].

Some authors as De Silva et al. [15] have investigated the brain function of obese patients during exposure to food pictures and intravenous infusion of Ghrelin with so-called functional magnetic resonance imaging. The investigations have revealed increased activation in the amygdala, orbitofrontal cortex, anterior insula, and striatum Furthermore, there are hypotheses that suggest that effects of ghrelin on the response of amygdala and orbitofrontal cortex are correlated with self-rated hunger ratings. Cholecystokinin (CCK) is another known gut hormone, which plays a role in food intake [25]. The experimental model confirms that CCK is secreted postprandially by the I cell of the small intestine into circulation, and it has a short plasma half-life of a few minutes. The investigations and studies into the function of Gastrointestinal hormones reveal that they play a significant role as mediators and triggering factors of weight regain in each patient. The process of investigation and adaptation of appropriate laboratory or Clinical tests to confirm that in clinical practice is too far now! However, the understanding and knowledge about secretion and expression of Gastrointestinal hormones can give us the basic selection criteria of Bariatric/Metabolic procedures in candidates of weight loss surgery and predict the long-term results of achieved or expected weight loss or weight regain.

The weight loss response after B/MS varies widely between individuals [6]. A part of this variation is probably due to genetic factors, as close biological relatives tend to have quite similar responses to weight loss interventions [19]. Several studies have tried with limited success to explore the significance of potential specific genetic determinants of the individual variation in weight loss after B/MS [2, 4, 5, 7, 8]. Reported studies of patients undergoing weight loss surgery have also pointed out a relationship between weight loss and genetic markers, associated with abdominal obesity. Anatomy and physiology of human body are individual; however, the polymorphisms of body fat distribution have been suggested to control the growth of human adipose tissue in three main pathways. The first one is so-called Adipogenesis. The second one is known as angiogenesis, and the third one is named as non-specified transcriptional regulation [26]. The first two pathways are responsible for adipose tissue function and expansion. The impairment of those two mechanisms can lead to metabolic disturbances through induction of hypoxia, inflammation, and fibrosis in the tissue [10]. The effects of fibrosis and reduced angiogenesis in adipose tissue are alerting factors for organ dysfunction in Morbid obese patients. Furthermore, fibrosis of adipose tissue may attenuate weight loss response after gastric bypass [1, 27]. Several hypotheses suggest that various genetic factors determinant for abdominal obesity and for weight loss responsiveness following surgical interventions may work via common pathways in adipogenesis and angiogenesis. One study has revealed that the association between Genetic Risk Score (GRS) and weight loss response to B/MS might be explained by the association between specific genetic markers and baseline anthropometrics, especially BMI [28]. Baseline BMI is known as a predicting factor for response to weight loss interventions. The choice of weight loss phenotype is therefore of great importance in this type of studies, investigating the association of weight loss and weight regain due to Genetic Factors. The same authors suggest that for mathematical reasons, the achieved BMI and excess weight loss variables are inversely associated with baseline BMI in B/MS cohorts [28]. Angiogenesis may be one of the mechanisms that govern the individual variation in response to weight loss treatment by possibly affecting adipose tissue flexibility.

Those studies open new horizons for surgical management of Morbid Obesity in patients with lower BMI but significant abdominal obesity and adipose tissue there. The studies also give the possibility to predict which procedures are most appropriate in such patients and what is the risk of WR on a long-term basis.

5. Gender, ethnic, and racial factors for weight regain after bariatric/metabolic surgery

Despite the overall success of bariatric surgery, weight loss and comorbidity remission appear to vary considerably across patients and procedures [2, 4, 5, 7, 8, 19, 29, 30]. Several studies, including a recent meta-analysis [31], have suggested that race is an important factor associated with weight loss and possibly comorbidity remission after BS [14, 24]. However, many of those reports represent single-center series with small numbers of patients. Furthermore, few of those studies have Data on the procedures such as: Sleeve Gastrectomy, Roux en Y Gastric bypass or one anastomosis Gastric bypass, comorbidity remission, or the effect of other socioeconomic variables.

The different aspects of social environment in Morbid Obese patients may also contribute to outcome after B/MS. Some studies have made efforts to allocate the spatial distribution of fast-food restaurants and supermarkets in connection to the residence of patients who have had weight loss surgery. The main conclusion of those studies is that access to foods meeting recommended dietary standards is an independent indicator for WR. They have also revealed a race difference despite the incomes of the population. Areas, predominantly inhabited by black people, regardless of income, have not had an adequate access to good-quality foods, compared to predominantly white, higher-income communities [32]. The infrastructure of the urban or non-urban areas also appears to contribute to the spread of Morbid Obesity in different living environments as indicator for WR. Transport links for commuters and access to nearby recreation centers are also contributing benchmarks, which can predict weight regain after B/MS. Lack of such facilities and transportation is isolating patients after surgery of effective postoperative follow-up and access to healthy lifestyle environment. There are also racial differences in understanding of good-looking body size. Review of surveys for body size outlines the prevalence of white obese women, who are looking for options of weight loss surgery or Gastric bypass due to impairment in quality of life, despite having lower body mass index values than the other race and sex groups [23]. The black men with Morbid Obesity are on the other pole of those surveys—they have the least social impairment with Obesity. The summary of those surveys reveals that ideal body size for themselves and the opposite sex are larger for black individuals than for white individuals [26, 33]. Morbid obese individuals in the black population have less social pressure to lose weight, but they can have pressure to lose less weight after B/MS by relatives and community [23]. Discrepancy between achieved and expected weight loss is the most listed common reason for dissatisfaction with surgery for both black patients (84%) and white patients (76%). The suggestion is that it might happen when there is patient–clinician discordance in racial identity [34]. Goleman et al. have revealed in their study that: “Gender and racial/ethnic background predict weight loss after Roux-en-Y gastric bypass independent of health and lifestyle behaviors” [35]. According to the authors: “non-Hispanic black men had significantly greater weight loss compared to non-Hispanic white men (p < .05).” The opposite, other studies do not reveal any difference in weight outcome between racial/ethnic groups of women, living in one and the same area. It means that socioeconomic factors and eating behaviors are more important predicting factors for WR than race and sex. However, it is known that patients with B/MS, who drink more diet soda than mineral water, have a higher percent of WR after surgery, independently of health status and lifestyle behaviors, age, and weight at the time of surgery. Another study has shown that blacks but not Hispanics have had a lower %EWL, compared to whites at 6 months after weight loss surgery. An interesting finding is that blacks have had a lower %EWL than Hispanics at every time point during the follow-up of patients [20]. The weight regain among different races varies, and it is evident even from the criteria for Bariatric/Metabolic Surgery in Europe, Asia, and the United States about BMI. Data suggest that there are significant differences in the prevalence of weight regain among patients post B/MS on different continents. Some of the published longest follow-up reviews have shown mean weight regain of about 4% after Roux-en-Y gastric bypass (RYGB) 3–7 years after surgery [32]. It contrasts with other studies, predominantly from Europe, which have reported that every fourth patient after RYGB or Sleeve Gastrectomy surgery can regain more than 15% of their body weight 5 years after the primary procedure [4, 5, 14]. It is also well-known that Asians are more prone to Diabetes Mellitus than white people with the same degree of BMI. Interestingly, there are significant differences in the algorithm for weight loss surgery in Asia and Europe, for example. The inclusion criteria for B/MS in Asia are lower with 2.5 kg/m² in each category of BMI. Surgery is also highly recommended for patients with Diabetes type 2 and cutoff BMI of 37.5 kg/m² compared to BMI over 40.0 kg/m² in Europe. The recommendations in Asia for Metabolic surgery suggest that patients with DT2 and BMI between 32.5 and 37.0 kg/m² should also be considered as candidates for Metabolic surgery, if their DT2 is poorly controlled. The review of data suggests that Asian patients will have lower WR up to 5 years after surgery due to lower threshold inclusion criteria for surgery as lower BMI. Because of differences in the baseline body height and weight, and body composition, it is not completely grounded to interpret the weight loss on the Asian communities according to Westerner physical standards. That is another evidence that WR on different continents and in different races is variable and individual approach and assessment of patients before or after BS are mandatory. The gender of the patient is another main contributing factor for WR after Bariatric/Metabolic Surgery. Several meta-analyses have revealed higher relative weight loss in men compared to women. Weight loss surgical outcome appears to be in favor of WL in men. That conclusion is based on data from two meta-analyses. Our experience can confirm the results of the one of those meta-analyses that female Obese patients are twice more likely to investigate and seek ways to lose weight than male patients. However, male patients can lose effectively more weight than female patients, and it can be up to 40% more likely successful [10]. There is a discrepancy on studies about influence of gender on weight loss and WR after B/MS. Some of them highlight male gender as an independent factor. On the other hand, other studies emphasize the role of exercise, diet, and eating behaviors as important factors for induced weight loss and deny the role of gender as indicator for WR [10, 36]. We are in favor of the second group of studies, because literature review of outcome after Bariatric/Metabolic Surgery in English and German language has shown no distinct difference in gender. That criterion is not reliable to give a definite answer, if a male or a female Morbid Obese patient with one and the same BMI is a better candidate for any weight loss procedure. Those six studies [37, 38, 39, 40, 41, 42], which have detected better outcomes for male patients B/MS, are probably focused on gender mostly, rather than of type of procedure, BMI at time of surgery, and type of the procedure. It is known that female patients are seeking more often Sleeve Gastrectomy as option for weight loss or even Gastric Balloon. Male patients, due to higher BMI, are probably more open to Gastric bypass options than to Gastric Balloons or Sleeve Gastrectomy. The dilemma with gender is observed in the reviewed nonsurgical studies about the association between weight loss and gender. We have found 16 studies, which report no gender differences. The opposite, another 16 studies have pointed better weight loss in men compared to women. Unfortunately, most of the reviewed studies report gender difference in absolute weight loss. Although, it is known that relative weight loss is a more accurate criterion of measurement about detecting gender differences. Overall, systematic reviews confirm that women more likely not to achieve better weight loss than men. We have a worse situation, looking at studies and reports for WR after B/MS. The data are less conclusive about gender difference as predicting factor for WR. Most of all reviewed studies, mentioning WR, are in favor of no gender difference. There are three studies that have reported less WR in men, and other two studies have reported better weight loss maintenance in women. We would suggest that mandatory next step is to be initiated a conduct in Europe, Asia, and America with focus on gender differences in weight loss and WR, in particular to provide additional information and knowledge about potential reasons and solutions for treatment outcome in female and male bariatric patients.

6. Behavioral, dietary, lifestyle, and psychological factors

According to different authors [10, 23, 36, 43], there are four eating and lifestyle habits, independently associated with greater probability of post-surgical WR - Table 1. Those four types of post-bariatric surgery patients are called: a “sweet-eater,” a “grazer,” lifestyle habit as sedentarism, and patients consuming more daily calories or alcohol. A “sweet-eater” is someone who eats 50% or more of carbohydrates or consumes only simple carbohydrates. A “night eater” is defined as someone who three or more times per week consumes ≥50% of daily calories after 7 PM, who had difficulty sleeping, and who reports not being hungry at breakfast. Alcohol consumption is important and has been determined as independent factor for weight regain. Those patients are categorized in two groups: those drinking alcohol ≥2 times per week vs < 2 times per week. Sedentarism as definition describes the habits related to an inactive lifestyle, which can cause health problems such as Obesity in some people. There is another disorder, known as Binge eating Disorder (BED). That type of disorder led to implementation of one anastomosis Gastric bypass in Asia first and then on other continents, and it is associated with food culture of population in different countries. One of the definitions of BED describes it as eating substantially large amounts of food within short periods of time, accompanied by a sense of loss of control and feelings of disgust, guilt, and/or depression after binge episodes [34]. Approval of one anastomosis gastric bypass as accepted by IFSO standard weight loss surgical procedure significantly increased the number of patients with binge food disorders as candidates for B/MS. Their number varies from 10 to 40% according to available published officially results on Bariatric Registers. However, that inclusion criterion did not increase or propose an algorithm for a robust pre-operative investigation of those patients or adequate screening results for outcome after bariatric surgery. Therefore, we “branded” a proportionally huge number of patients as those with “binge food disorder,” who qualify for a weight loss procedure. But those patients aren’t diagnosed or treated for BED before surgery. They probably have certain aspects of the disorder (e.g., loss of control about food and eating), and they may emerge post-surgery, potentially resulting in negative long-term weight loss outcomes or weight regain [36]. The conclusion is that we need beforehand preoperative assessment of patients with BED by experienced behavioral health professionals. The process of diagnosis and management of patients with BED, candidates for B/MS is critical, as the underlying dynamics of the disorder usually will persist after surgery [27]. Effective treatment for BED or maladaptive eating before surgery potentially will predict outcome of surgery. Such treatment will help the patient to cope successfully with depression, anxiety, or trauma after weight loss surgery. The process of long-term management must include nutrition counseling, medical care, and follow-up to 5 years after surgery. Outcome of patient’s treatment as individual or in a group with similar patients plus involvement of family therapy is a significant predicting factor for WR after one anastomosis gastric bypass [44]. The absence of such a multidisciplinary approach to treatment is a potential risk for the eating disorder to persist or morph into another form of eating disorder as grazing. According to most definitions, available on Intranet, “grazer” is a person who eats snacks or small food portions several times a day, without consuming a primary meal. Grazing is a more serious behavioral health disorder, as it can develop a higher risk of vomiting and gastrointestinal symptoms. According to some Bariatric surgeons, dysphagia and dumping after weight loss surgery can teach the patients to change their eating habits. Unfortunately, that statement is wrong. Regular vomiting postoperatively can cause nutritional deficiencies, dental caries, esophagitis, and gastric ulcers, all of which can further impact food choices and intake [43]. The misperception among some patients that frequent vomiting helps to prevent WR should be corrected and noticed by responsible Dietitian and surgeon on follow-up clinic reviews immediately and negative effects of the condition to be explained and treated accordingly. Even patients who lack a formally diagnosed eating disorder can lose control over their eating habits after B/MS and that loss of control might increase around the 2-year point [26, 33]. Literature review confirms that loss of control overeating or appearance of grazing after surgery is associated with less excess weight loss, greater WR, and decreased perceived quality of life [23]. It is known that patients who engage in grazing behaviors two or fewer times per week after surgery have poorer percentage of excess weight loss and larger weight regain than those who had not has such a problem.

Type of eating disorder	A “sweet-eater”	Grazer	Sedentarism	Night eater
Definition	Someone, who eats 50% or more of carbohydrates or consumes only simple carbohydrates	Eating frequently at irregular intervals’ – not quite the same as snacking, but probably more frequent.	The habits related to an inactive lifestyle which can cause health problems	Someone, who 3 or more times per week consumes ≥50% of daily calories after 7 PM, who had difficulty sleeping and who reports not being hungry at breakfast.
Psychological Factors	Depression and anxiety, self esteem	Triggered by stress, boredom, and emotional distress and worsens with “mindless eating” while watching television, surfing the internet, attending social meetings, or working in foodservice settings.	Generally inactive with mental and health problems, family history psychological disorders	Sleeping disorders, alcohol problems, depression, anxiety
Weight regain after B/M Surgery	Regain of 10–25% of EWL	Regain of 45–60% of EWL	Regain of 25–30% of EWL	Regain of 15–40% of EWL

Table 1.

Morbid obese patients with known eating and lifestyle habits and WR.

There are also so-called: “Other Maladaptive Eating Behaviors.” Dietitians and Nutritional specialists have found that maladaptive eating behaviors may also develop in some patients. It is explained that attempts to avoid vomiting after B/MS are linked to the development of food aversion, protein malnutrition, and micronutrient deficiencies. Unfortunately, those maladaptive disorders also influence long-term weight loss outcomes and quality of life [45]. There is another group of patients with eating disorders. They generally avoid solid foods and eat softer, high-calorie foods such as chocolate, candy, and ice cream. The consumption of excess calories, particularly from refined carbohydrates and saturated fats, is another objective predictor of WR in such patients. Maladaptive eaters among patients with weight loss surgery consider easier to swallow soups, crackers, and cheese than solid foods. Overconsumption of softer, calorie-dense foods (“soft food syndrome”) provides inadequate nutrition and decreased satiety. Another condition, which ultimately contributes to excessive energy intake and weight gain. There is also another group of patients who prefer fully to engage in restrictive model of eating, failing to consume adequate calories due to an intense fear of stretching the stomach pouch and regaining weight. There is a psychological factor in those patients: preoccupation with weight and body image, but that condition can lead to macro- and micronutrient deficiencies and eventual WR [33]. Bariatric surgery developed another restrictive eating disorder. It is known as: “post-surgical eating avoidance disorder” or PSEAD. The disorder is described as eating very little to avoid WR or experience of an almost “phobic” reaction to food. Healthful eating habits should be reinforced months before surgery. Active role of Dietitian and engagement of patient are mandatory to prevent the onset of maladaptive eating patterns, gastrointestinal distress, and WR. The Dietitian should be certain that candidates for weight loss surgery have made significant behavioral changes involving nutrition and food as eating slowly and exercising portion control. The use of cognitive behavioral strategies to encourage mindful eating and appropriate food choices is another successful part of the game about the process of teaching [26]. The regular follow-up from multidisciplinary team members will recognize early maladaptive eating behaviors or food aversions, expressed by patient, and will encourage him to maintain adequate lifelong nutrition, and not rely on BS alone to improve their weight loss outcomes and health benefits. The early changes in total energy intake and macronutrient composition during the first 6 months after surgery are found to be a predictor of long-term success with 10 years follow-up [21, 25]. Data confirm that eating 100 additional daily calories is associated with a 30% increase in odds of WR 3–4 years after BS.

It is known that preoperative physical activity levels and eating style do not correlate with maximum weight loss. However, there is a negative correlation between preoperative physical activity levels and external eating and a positive correlation between physical activity levels and restrained eating [22]. According to a paper, presented at IFSO 22nd World Congress; August 29–September 2, 2017, in London: “There was a less weight regain in patients who reported more [physical activity] after RYGB. Eating style does not seem to affect weight regain” [3]. A study from 2021 confirms that low level of physical activity and longer sedentary time have occurred more frequently in those with high WR and longer time since weight loss surgery [28]. Mental health conditions are common among bariatric surgery patients. Abnormal eating patterns, binge eating disorder in particular: depression, alcohol and drug addiction are reported as predictive factors of weight regain after BS [23, 24]. Psychological assessment and identification of those patients preoperatively are a major contributing factor for good long-term results after Bariatric/Metabolic Surgery. Unfortunately, the limitations of funding for weight loss surgery and the whole process of preparation of a patient for such type of treatment are an ongoing problem in Europe and all over the world. Patients who choose BS must be educated to understand that Obesity is a chronic disease! Bariatric/Metabolic surgery is only one of the tools, which can effectively help the patient to achieve significant weight loss, but inadequate postoperative adherence to recommendations can override that tools’ efficacy, leading to weight regain.

7. Weight loss procedure as a technique and selection of type of operation as a factor for weight regain after bariatric surgery

The data review of different search engines about WR after well-known weight loss procedures worldwide is presented in Table 2. The data represent current estimated success of those procedures on a long-term follow-up. However, they do not represent the spread of different procedures and their popularity around the globe.

Type of procedure	WR after 2 years	WR after 3 years	WR after 4 years	WR after 5 years	WR after 10 years
Lap band procedure	5% with >20% of EWL	25% with >50% of EWL	38% with >40% of EWL	Over 60% regained >50% of EWL	No data, most bands removed
Sleeve gastrectomy	2% with up to 5% of EWL	12% with >20% of EWL	18% with >35% of EWL	25% with >40% of EWL	40% with >40% of EWL
Roux en Y gastric bypass	1% with up to 5% of EWL	2% with up to 5% of EWL	3.5% with 10% of EWL	3.9 to 4.0% >10% of EWL	4.5% >10% of EWL
One anastomosis gastric bypass	0.2% with up to 5% of EWL	1.0% with up to 5% of EWL	3.0% with up to 5% of EWL	3.5% with >10% of EWL	5% with >5% of EWL
Duodenal switch	0%	0.8% with up to 2% of EWL	1.5% with up to 5% of EWL	2.0% with >5% of EWL	2.5% with >5% of EWL

Table 2.

Weight regain due to type of weight loss procedure: (electronic database data, including PubMed, MEDLINE, Embase, CINAHL, Web of Science and Scopus).

Sleeve Gastrectomy is the most common weight loss procedure all over the world so far. Its prevalence in United States and parts of Asia can be explained with eating habits or preferences of the patients there. For example, India’s population is more than 50% vegetarian. Malabsorptive procedures such as Roux en Y or one anastomosis Gastric bypass have significant side effects on vegetarian patients and they struggle to compensate their protein and nutrient balance. So, the practice and experience reversed the type of weight loss procedures to Sleeve Gastrectomy (SLG) there. The growing number of weight loss operations all over the world, according to IFSO survey in 2016 total number of procedure, was 700,000 [46], provide enormous data about Bariatric procedures and patients. However, weight regain after bariatric surgery is one of the related topics with a relatively limited number of publications [47]. Long-term results of bariatric patient series reveal that after 2 years postoperatively, patients’ rate of losing weight tends to decelerate [48]. Despite those results, Sleeve Gastrectomy is still the preferable operation for weight loss for patients and surgeons around the world. The numbers of Sleeve procedures are significantly higher than bypass procedures, according to data from IFSO Register and explanations of that status are not associated with long-term outcome and probability for WR [22]. Long-term results have shown that Sleeve Gastrectomy procedure is associated with significant WR within 10 years after surgery. The other main problem with that weight loss procedure is about development of a restrictive eating pattern and intractable gastroesophageal reflux, requiring revisional surgery in up to 20% of patients after primary procedure. The aspects of weight regain after SLG have been discussed in several publications; however, there are no systematic reviews, encompassing all surgical issues about the procedure. Anatomical/surgical factors of weight regain after LSG are identified as: an initial large sleeve, incompletely resected fundus, and a large remnant antrum. We think there are three other issues about WR after Sleeve Gastrectomy as a technique and patient selection: Medical tourism as a factor for spread of the procedure, applicable to different Body Mass Index, even in super Obese patients as a first-stage procedure, the growing number of weight loss procedures performed privately, rather than in public Hospitals. The use of different bougies or dissection of the stomach to 2 or 4 cm above the pylorus has been investigated, and there are no standards about impact of that on weight regain. Several studies have showed no difference in dissection of the antrum as a predicting factor for weight regain after SLG. The learning curve of the surgeon and dissection around the short gastric vessels and left crura are also factors contributing to WR after LSG, according to different studies [2, 4, 5, 7, 8, 49, 50]. Medical tourism and offer of the SLG in private are another contributing factor for WR. Interestingly, there is a growing amount of data for patients, admitted to UK NHS hospitals in emergency after SLG abroad. One such example is about a case of our practice: a 45-year-old lady, who had a SLG in Turkey. She has developed bleeding from staple line, she has been transfused with 2 Units of blood there and sent home back on a commercial flight. The lady has been admitted from Airport to our Hospital with a HB of 89.0 g/l and urgent CT scan showed a big hematoma around the greater curvature of the stomach and spleen. Her management has been conservative, and outcome has been uneventful. However, she has been followed for 6 months only after surgery and her BMI at time of admission was 52.0. There are several other reports for admission of patients 1–2 weeks after SLG abroad, due to severe nausea, vomiting, or even dehydration and motility problems. It is known that about 15% of population in the United Kingdom has motility disorders of the esophagus. As we mentioned above, those disorders plus reflux after SLG are important factors for WR in those patients. The robust pre-operative investigations of bariatric patients and selection of the appropriate type of weight loss procedure are the key for long-term good results and prevention of substantial WR. Unfortunately, the economy recession and restrictions of funding about weight loss surgery are a serious concern about the increase of Bariatric procedures in NHS and the right of more Morbid Obese patients to have a proper selection and access to weight loss surgery. The other main issue is that in some parts of the United Kingdom, the only offered bariatric surgery in NHS is the Sleeve Gastrectomy. The patients with BMI over 50.0 are struggling to get an access for a bypass procedure, funded by NHS, in another Bariatric Center due to administrative problems. Weight regain after Roux en Y or one anastomosis Gastric bypass is also reported and documented. The WR after those two procedures is less than SLG, and the main reasons are associated with the volume and shape of the Gastric pouch, the diameter of gastro-jejunal anastomosis, and the length of biliary limb. The Surgeon, who first proposed mini-gastric bypass–Rutledge, describes his vision that dumping, as outcome of the procedure, contributes significantly to weight loss after surgery. Unfortunately, the motility of esophagus as a factor for WR after mini or one anastomosis gastric bypass is not investigated robustly so far. The quick transit of food from esophagus to stomach can accelerate appearance of eating disorders and minimize the effect of restriction. Most of the experts in bariatric surgery recommend the pouch-jejunal anastomosis not to be created immediately under esophago-gastric junction as the pouch will not be functioning optimally in terms of weight loss and long results can be disappointing. They also recommend the anastomosis between the pouch and jejunum to be on the side of the greater curvature and a length of 2–4 cm of the lesser curve of the stomach to be incorporated in the pouch.

It is known that Poiseuille’s Law in physics postulates that the flow rate through a tube is inversely proportional to its length. Slow flow or emptying of the pouch is desirable after gastric bypass and contributes to the restriction [45, 51]. According to that law seems that the shape (length and diameter) may be rather more important than the size itself [52]. Another law in physics, known as LaPlace Law, postulates that the pressure required to distend a structure (tube) is inversely proportional to its radius. Interestingly, those two laws in physics have their application in creation of gastric pouch during bypass surgery. The shape and form of the pouch plus diameter of anastomosis with jejunum are mandatory for the optimal function of the gastric bypass. Literature review has confirmed that longer and narrower gastric pouch has a less dilatation in time after gastric bypass surgery. It combines slower emptying of the pouch, less probability for dumping syndrome, and less stretching 2 years after surgery. The Fobi Pouch Gastric bypass is an example for such a gastric pouch; however, evidence of long-term results is necessary to completely implement the postulate of the mentioned above physics law in Bariatric surgical practice [50]. WR, which is seen 3–5 years following laparoscopic gastric bypass surgery, is often explained because of enlargement of the pouch [22]. For durable restriction and therefore weight loss, a long narrow pouch is recommended. The length of pouch after one anastomosis gastric bypass (OAGB) is important about bile reflux and its complication also can contribute to WR.

There are still many debates about postoperative bile reflux after mini or one anastomosis gastric bypass and its significance about quality of life of patients and WR. The accepted standard in the technique is length of the sleeve—more than 16 cm. However, there are also different “tips” for avoiding the bile reflux and hence weight regain 5 years after the procedure. There are no statistically significant data to confirm the importance of the proposed “tips.” The BMI over 50.0 kg/m² before surgery, age of the patient at time of surgery, concurrent eating and metabolic disorders, length of the biliary limb, and diameter of the anastomosis are probably the predicting factors for outcome and WR after gastric bypass surgery [51, 53]. Innovations and suggestions as Fundo-Ring OAGB, wherein one anastomosis gastric bypass the proximal part of the pouch is wrapped with a fundus of the excluded part of the stomach to treat bile reflux and WR, are promising and interesting. However, long-term results are needed. The banding of Gastric pouch or the Gastric Sleeve with Fobi ring is another promising technique for surgical management of weight regain, and the long-term results will reveal more detailed information about feasibility and effectiveness of that proposed technique. The size of gastro-jejunal anastomosis is another important factor for WR. The recommendations are about a diameter of the anastomosis of 1.5–2.0 cm. Unfortunately, such diameter of anastomosis is a significant problem in the United Kingdom, whereas patients have esophageal dysmotility problems and their eating habits are different of those in patients from Europe and Middle East. Due to prevention of early complications with stricture and vomiting after Roux en Y Gastric bypass surgery, most Bariatric Centers in the United Kingdom prefer to do a stapled gastro-jejunal anastomosis with 45 mm reload. The short-term results and outcome of those patients are excellent; however, about 40% of them have a risk to develop significant WR 3–5 years after surgery. Unfortunately, the International Bariatric Registers are not giving adequate and exact information about the association between WR and the diameter of Gastro-jejunal anastomosis. Endoscopic management of the gastro-jejunal anastomosis as a size is effective and safe option in experienced hands as a first step for management of WR after Roux en Y Gastric bypass [54]. It allows several attempts in first instance to treat wide anastomosis or even peptic ulcers and is highly recommended opposite revisional surgery for management of WR in high-volume centers [51].

The length of biliary-pancreatic limb (BPL) has been the subject of several investigations about its effect on weight loss and hence WR after Gastric bypass surgery. The distalization of the biliopancreatic limb is associated with greater weight loss even in revisional surgery. The suggestion is based on data that patients with short biliary limb—between 50 and 60 cm, achieve less weight loss and regain a higher percentage of EXL within 5 years after surgery [14, 35]. However, the lessons of human anatomy should not be forgotten. The length of a small bowel in a human body is proportional to his height. The longer biliary limb in a bariatric patient postulates measurement of total small bowel length or at least of the common channel in order to avoid serious postoperative complications such as protein malnutrition and diarrhea [40, 55]. A study from the USA describes a racial difference in patients with distal biliary limb. According to Khattab et al. [34], patients with Afro-American and Asian origin do not tolerate the distal gastric bypass as well as white patients. There are other authors, who have several arguments toward the significance of the biliary limb length [35]. They think that reduction of common channel length should be tailored individually and there are other concomitant factors, which are responsible for weight loss and WR in every patient [35]. That factor, plus discrepancies in small bowel measurement during surgery, can play a significant role in mechanisms of weight regain after B/M Surgery.

Several experimental studies have tried to interpret the presence of undiluted bile acids in the distal small bowel. They suggest that there are specific receptors, which are triggered by undiluted bile acids in the L cells in ileum, and those cells are responsible for enhanced release of GLP-1 and PYY hormones in the small bowel. Their theory explains why serum bile acid concentration is after Roux en Y Gastric bypass and that can lead to increased energy expenditure [17, 51]. Modern theories about better weight loss after malabsorptive procedures are based on hormonal mechanisms and interactions, which at the end achieve lower HbA1C levels, found among the group with longer biliary limb. Therefore, nutritional disturbances are more pronounced, and the diarrhea score significantly increased in the longer BPL group due to eating habits of the patient [24]. It is likely that these side effects will be observed in future reports on the patients with a longer BPL. So, the BPL length as a factor for WR is still in debate, and more randomized and long-term studies are required to obtain medical-based evidence for importance and influence of BPL over WR after Roux en Y Gastric bypass or one anastomosis bypass surgery. The length of BPL is in direct correlation with BMI of the patient nowadays. The standard length of BPL is 100 cm in length in patients with BMI between 40.0 and 48.0. When BMI is more than 48.0 and height of the patient is over 170 cm, BPL length is recommended to be 120–150 cm in length and the patient to have a common channel at least of 250 cm to avoid severe malnutrition, diarrhea, and vitamin deficiency.

Bariatric/Metabolic procedures, proposed for management of WR as SADI-S procedure, biliopancreatic diversion, and duodenal switch have been well investigated and documented, and their routine use has been largely abandoned due to abovementioned possibilities for complications and nutritional problems. Those patients need very close review and support by specialized Clinics and Hospitals for management of such nutritional and malabsorptive issues more than 2 years after primary procedure. However, the data of medical-based evidence and Guidelines of Bariatric Surgical Societies around the world are in a discrepancy about follow-up of patients after weight loss surgery. Data suggest that all B/MS patients to be reviewed and followed almost 5 years after surgery, but Guidelines recommend a cutoff up to 2 years after primary procedures, leaving a significant and not relevant burden of follow-up to General Practitioners.

8. Summary

Most Morbid obese patients emphasize on importance of having someone, who can give them support in a way that they have felt understood. Most of them also expect bariatric surgery to end their struggle with weight and eating [56]. Unfortunately, Bariatric patients are often unprepared for weight regain and react with emotional distress, i.e., hopelessness, discouragement, shame, and frustration. Regaining weight might be a devastating experience that contribute to a negative spiral in weight management. Negative self-image, maladaptive eating behaviors, substance’s use, and overall impaired psychosocial functioning in turn have been associated with internalized weight bias and further weight management difficulties [10, 14, 23, 24, 26, 28, 33]. Postoperative alcohol use has been identified as a predictor for weight regain and even severe episodes of pancreatitis, which unfortunately caused death in two of our cases on 10 years’ follow-up after BS. Addiction transfer refers to a shift, where food rewards are replaced with other substances post-surgically, which may also contribute to weight regain [24]. Procedures, perioperative protocols, and post operative management for bariatric surgery will evolve over time. Solution of those complex problems and management of WR require a longer follow-up and support of experienced multidisciplinary teams. Most of the contributing factors of WR are summarized on Table 3. However, the discussion for a funded and patient-oriented routine review by experts and specialists in Bariatric/Metabolic Surgery up to 5 years after the primary procedure is still open. We need a more serious and honest debate about extended funding of those activities by Governments and Health Insurance Funds.

Psychological background of patient	Body Mass Index and waist circumference at time of surgery and	Race and social status	Is procedure relevant to BMI and co-morbidity	Post op support and follow up
Anxiety and depression not treated effectively before surgery	BMI over 50 or 55	Poor social status, Lives in a community, where obesity is not a health issue	Lap Band or Sleeve Gastrectomy in patients with BMI between 42 and 50	Surgery done privately
Eating and binge eating disorders	minimal or no weight loss before surgery	Female patients with Hispanic or Afro American origin	Anastomosis of more than 2.5 cm and larger pouch	No national system for regular follow up
Mobility and physical activity	<50% of required weight loss on second year after surgery	Lack of healthcare system for tackling of Obesity	Biliary limb less than 100 cm	Lack of Dietitian review in the first 3 years after surgery
Alcohol intake. Self-control and feeling of disgust	Waist circumference more than 115 cm in female patients	Family support and community support	History of DT2 and Sleep Apnoea more than 5 years	Lack of regular psychological support after surgery

Table 3.

Summarized predicting factors for weight regain.