A Framework of Food Cravings and Weight Loss after Bariatric Surgery: Application of the Cognitive Processing Model

Introduction

The Centers for Disease Control's National Center for Health Statistics (2007) report that 66% of the U.S. population is overweight or obese. The proportion of the population experiencing obesity has reached epidemic proportions and is expected to continue to increase at such a rapid pace that, for the first time, life expectancy is expected to decline in the 21st century due to the effects of obesity.^1,2

Bariatric surgery is a common therapeutic option for the treatment of obesity. The American Society for Metabolic and Bariatric Surgery (ASMBS) estimates approximately 205,000 bariatric surgery procedures were performed in 2007, which is a 15% increase from 2006. ³ While the surgical procedure is associated with low complication rates, the success of the surgery is determined by long-term outcomes, especially weight loss, and these outcomes are highly variable. Approximately 50% will experience at least some weight regain postoperatively.^4–6

While not exclusively responsible, one important known contributor to weight regain is binge eating, ⁷ a behavior that is often precipitated by food cravings. Food cravings are defined as an overwhelming urge or all-consuming intense desire to eat. ⁸ Research on craving shows that as one abstains from a desired substance, or if one is prevented from using it (restrained), cravings for the substance intensify, particularly if the substance has been chronically misused.^9–11 Gastric bypass surgery physically restrains patients from eating in the pattern and amounts they did previously due to a pouch size that is created to hold approximately 30 cc of food. ¹² This restraint leads to a scenario where some patients may experience intense and chronic cravings that result in greater risk of binge eating (at least to the degree possible with the surgery). Repeated occurrences of this behavior result in pouch stretching, and ultimately in the nullification of the physical benefit of the surgery. The purpose of this paper is to present a theoretical framework that investigates cravings as a predictor of weight loss after surgery, based on a cognitive processing theory of craving, ¹¹ craving being defined as the intense desire or longing for a particular substance. ⁸ Because of the similarities in binge eating and compulsive eating identified in the substance abuse literature, the purpose of this paper is to focus solely on craving and binge eating as a contributing factor to weight regain.

Background

Patients undergoing bariatric surgery can expect to lose between 60% and 70% of their excess weight, with some studies reporting excess weight loss as high as 81%.^5,13 Excess weight is determined by calculating the ideal weight of the individual (based on the Metropolitan Height and Weight Tables) then subtracting the ideal weight from the actual weight of the patient. The significant weight loss experienced after surgery results in a reduction in life-threatening comorbidities. In a meta-analysis of more than 20,000 patients, type 2 diabetes, sleep apnea, and hypertension were eliminated or improved in 77%, 86%, and 62% of patients respectively. ¹³ These results support that the risk of invasive surgery for this population is outweighed by the potential health benefits of the resulting weight loss.

While most patients achieve significant weight loss and resolution of these comorbidities, a substantial minority, approximately 20%, will regain all of their lost weight. ⁴ Up to half of all patients will experience at least some weight regain in the first 2 years after surgery, and most weight regain occurs within 10 years of surgery.^4–6 Because weight regain results in re-emergence of comorbid conditions, there is substantial interest in better predicting who is at risk for weight regain and providing those patients with additional intervention to prevent this outcome. ¹⁴

The effective mechanism of gastric bypass surgery is the reduction of the stomach capacity, coupled with a malabsorptive effect of diversion of food and nutrients from the duodenum. ¹⁵ As long as the stomach pouch remains small, food intake is limited and the resulting caloric restriction results in weight loss or weight maintenance once a target weight is achieved. However, if the pouch is stretched as a result of food intake “challenges,” such as binge eating episodes, the benefits of the surgery are nullified. There is evidence, albeit not unequivocal, that binge eating is a risk factor for weight regain. ⁷ Understanding what motivates or leads to binge eating in this population is likely key to understanding risk for weight regain.

Similarities of Binge Eating Behaviors and Substance Use Disorders

There is substantial evidence that important similarities exist between binge eating behaviors and substance use disorders. ¹⁶ First, they share common diagnostic features. In the 5th edition of the Diagnostic Statistical Manual's proposed criteria for substance abuse disorder, binge eating meets four of the eleven criteria: (1) the substance is often taken in larger amounts or over a longer period than was intended; (2) there is a persistent desire or unsuccessful efforts to cut down or control substance use; (3) the substance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is like to have been caused or exacerbated by the substance; (4) craving or a strong desire to use a specific substance. In particular, both are characterized by a loss of control over moderate use (i.e., compulsive use). ¹⁶ Binge eating is characterized by both eating in a discrete period of time (e.g., 2 hours) an amount of food that is much larger than most people would eat in a similar time period under similar circumstances, and a sense of lack of control over eating during the episode (a feeling one cannot stop eating or control what or how much one is eating). ¹⁷ Second, the two disorders also share common neurocircuitry. Wang et al. demonstrated the similarities between obese and drug addicted subjects in levels of dopaminergic D2 receptor levels, indicating that similar to drug addicts, obese individuals are less sensitive to reward stimuli, likely because of the neuroadaptation that has resulted from years of substance misuse. ¹⁸ In both types of disorders, the dopaminergic mesolimbic reward system is activated when the substance is consumed.^19,20 Given that binge eating shares features with substance use in addicted individuals, it is reasonable to suppose that a theory proven valuable to explain relapse in individuals with addiction may also be valuable in understanding motivation to engage in binge eating in individuals with obesity.

Theoretical Framework

This paper seeks to demonstrate that the application of the cognitive processing theory of craving ¹¹ will improve prediction of successful treatment of obesity through bariatric surgery using models that have been studied in the drug and alcohol abuse population. The following narrative begins by describing this theory, its predictions, and evidence of the value of the theory in studying substance use among addicted individuals. Next, key concepts of binge eating as an automated process and craving are discussed. Finally, the theoretical framework for how the model applies to predicting weight regain following gastric bypass surgery is presented, as well as future areas of research. While there are other models that have been studied to prevent relapse, ¹² this study is the first to seek predictors of relapse in this patient population.

The Cognitive Processing Theory of Craving

The cognitive processing theory is based in learning theory, where it is proposed that over time, repeated behaviors become over learned and “automatized,” meaning that they do not require conscious attention to complete. In fact, an automatized behavior often requires cognitive resources to halt. Tiffany proposes that in addicted individuals, substance use becomes an automatized behavior, and that when an individual is in recovery, s/he must have cognitive resources available to block the performance of drug-taking behavior. That is, relapse is a result of learned behaviors and failure to maintain vigilance to keep from expressing the learned behavior (drug taking) or in the case of the bariatric surgery patient, restriction from the learned behavior, which is overconsumption of food.

Tiffany's theory also includes explanation of nonautomatic behaviors (where the behavior requires conscious attention). These occur in three primary scenarios: (1) when a skill is first learned; (2) when an automatic process is activated, but some environmental obstacle prevents completion of it; and (3) when a person actively attempts to prevent the execution of the automatic process. ¹¹ With this theory, the experience of craving is a non-automatic product that results from either scenario two or three. That is, when one is either prevented from using (where the obstacle is externally provided, as in the form of a surgically induced small stomach) or when one makes a conscious effort to keep from using (where the obstacle is internally generated), a strong urge to use may be experienced.

This theory can be applied to the bariatric surgery population, where binge eating and overconsumption of food have become an automatized behavior.^21–23 Halting the process of overeating once eating has begun requires considerable conscious effort and focused attention and vigilance, and in the case of patients seeking bariatric surgery, these conscious efforts have not been sufficient to result in behavior change in the past. Patients present for gastric bypass surgery seeking to obtain an obstacle—the small gastric pouch—to prevent them from performing the automatized act of overeating.

The cognitive processing theory predicts that when an automatic process is disrupted, as it is in the gastric bypass patient due to the new gastrointestinal anatomy, cravings will develop, ¹¹ which motivates binge eating and subsequent weight regain. ²⁴ The severity and frequency of cravings are important to measure and potentially address in order to halt the inevitable process of relapse (see Fig. 1)

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FIG. 1.

Food craving, binge eating and the cognitive processing model.

This model proposes that automatic eating behaviors are represented as grazing, binge eating, and compulsive overconsumption of food. Grazing is defined as a pattern of repeated episodes of overconsumption over a long period of time in conjunction with feelings of loss of control. ²³ Binge eating is defined as eating a large quantity of food accompanied by a feeling of loss of control. ²³ Compulsive overconsumption refers to behaviors where overeating is a passive behavior and occurs without the individuals awareness. ¹⁶ Basing this model on Tiffany's cognitive processing theory, the gastric bypass induces a disruption in the automatic eating behaviors defined above, and therefore elicits cravings, ¹¹ which are known antecedents to binge eating ²⁴ with a resultant relapse or weight regain.

Craving as a Concept

The phenomenon of craving is an important factor in the study of substance abuse, as cravings are commonly cited as a primary reason for relapse of addictive behaviors.^25,26 Craving is defined as an intense or overwhelming desire to consume a particular substance. ⁸

Craving is a multidimensional construct, but most experts agree that it results from classical conditioning in which the unconditioned stimulus is the drug of choice. Stimuli (such as sights, smells, emotions, people, places, etc.) that are repeatedly paired with the drug eventually acquire specific meaning and these cues can elicit a conditioned response. ²⁷ In the case of addiction, the conditioned response is intense craving—a motivational drive or “want” or “need,” which precedes the act of drug delivery (relapse for those attempting abstinence).

Tiffany's cognitive processing theory expands upon the classical conditioning theory of craving by proposing that craving is not solely the product of classical conditioning. It may also occur in the absence of cues, when an individual is prevented from performing an automatic behavior. ¹¹

Craving plays a critical role in undermining recovery in drug-addicted individuals; ²⁸ it is likely that it also plays a role in undermining successful continued weight loss in patients who have had bariatric surgery. There is empirical evidence that cravings are an antecedent to binge eating behaviors.^9,24,29 In addition, in agreement with Tiffany's model, restrained eaters, or those who are dieting, demonstrate a significantly higher level of food cravings than nonrestrained eaters.^30,31 It is notable that while binge eating is routinely assessed both prior to and following bariatric surgery (to the extent to which binge eating is possible postoperatively), very little work has been done to assess cravings in this patient population. In essence, the research in the area of understanding “relapse” in bariatric surgery patients has focused on the downstream behavior (binge eating) that results in unsuccessful weight loss; the present narrative proposes that it is theoretically sound and potentially valuable to assess the motivational state (e.g., the severity and frequency of craving) that ultimately leads to the unwanted behavior.

Discussion

In the substance abuse literature, there is evidence for cravings being positively correlated with drinking/use, and there is evidence for cravings being unassociated with drinking/use.^11,28 There is not unanimous agreement in the extant addiction literature about which theory about the relationship between craving and substance use is most accurate. ³² The equivocal nature of the data supports, however, that craving should be measured with multiple validated instruments and instruments that capture the multifaceted nature of craving. This review provides data to support positive associations between the automatized behaviors such as binge eating and food craving scores.^9,29 In further support of Tiffany's cognitive process theory, studies demonstrate that cognitive competition helps to decrease food craving scores. ³³ In one study of obese/overweight men and women, they were presented with questionnaires to measure the extent to which they endorse food thought suppression. In this study, thought suppression, which can be interpreted as when a person actively attempts to prevent the execution of the automatic process as per Tiffany's theory, was a significant predictor of binge eating and cravings, more so in dieters versus nondieters.^11,31 Such data may assist investigators in better understanding how and when craving is a predictor of drinking/substance abuse or compulsive overuse of food. The 5th edition of the Diagnostic Statistical Manual has proposed criteria to define substance use disorder with one of the criteria being “craving or a strong desire or urge to use a specific substance,” which supports the similarities between compulsive food consumption, cravings, and substance use disorder.

The craving model discussed in this paper (where the relationship between craving and use is unclear, but the relationship between use and relapse is certain) may also apply to the bariatric surgery population. Understanding cravings, binge eating, and postoperative weight regain in patients who have had bariatric surgery is an important area for research, since “relapse” is common in this population. While certainly binge eating in this population is associated with weight regain following surgery, how craving predicts binge eating and weight regain is unclear. The field needs studies that assess patients with multiple different craving measures to determine whether and which of these instruments show valuable predictive power for patients at risk for weight regain. Tiffany's theory of cognitive processing seems to provide the best fit for study over time, since cravings may change over time based on the disruption of the automatic process of binge eating behaviors that could lead to cravings. ¹¹

Future Implications

It is proposed that a fruitful area for future research in obesity is to determine the psychometric properties of instruments designed to assess craving severity in patients prior to and following gastric bypass surgery. Understanding cravings, binge eating, and postoperative weight regain in patients who have had bariatric surgery is an important area for research, since “relapse” is both common and life-threatening in this population. How and whether craving predicts binge eating and weight regain is unclear. The field needs instruments to assess patients' craving accurately to determine whether and which of these instruments show valuable predictive power for patients at risk for weight regain. Tiffany's theory of cognitive processing seems to provide the best fit for study over time, since cravings may change over time once the automatization of binge eating becomes weakened with continued practice at restraint. ¹¹ Once there is a better understanding of the influence of cravings on weight regain, specific interventions can be developed and implemented, with the ultimate goal of seeing greater long-term weight loss success in the bariatric surgery population.

Total healthcare costs attributable to the treatment of obesity/overweight individuals are expected to double every decade, reaching around US$900 billion by 2030 and accounting for 16–18% of total U.S. healthcare costs. ³⁴ The annual healthcare cost of treating comorbidities for individuals with a BMI of 25 or greater has been shown to be $8,759 per year on average, as compared to $5,245 for a person with a normal BMI. ³⁴ The high incidence of obesity presents a tremendous strain on the healthcare system, both in actual healthcare costs of treating comorbidities as well as the strain on resources consumed to treat these comorbidities.

Conclusion

With a better understanding of cravings and the subsequent behavioral response with food consumption, researchers will have the opportunity to identify those at risk for cravings, subsequent binge eating and weight regain, and develop interventions for therapy to stop the craving cycle. Extensive craving research has been conducted in the drug and alcohol literature indicating that craving has a role in substance abuse. In the bariatric surgery population, there is a paucity of research evaluating craving and the role of cravings before or after surgery. Future research aimed at measuring craving scores and associated weight loss after surgery may provide a foundation for a more meaningful and empirically driven presurgical and postsurgical evaluation and treatment plan to help ensure that the benefits of bariatric surgery are fully realized and sustained for this patient population.