Eating Pattern and Bariatric Surgery

Abstract

Bariatric surgery entails profound anatomical and/or functional modifications in the upper gastrointestinal tract, and consequently a marked change in the patient’s eating habits and behavior occurs. After adjustable silicone gastric banding, vertical banded gastroplasty and Roux-en Y gastric bypass, gastric restriction represents the most powerful factor able, mechanically and/or physiologically, to induce decreased food intake. Eating behavior modifications that lead to permanent reduction of food intake cause satisfactory long-term weight loss and maintenance. On the contrary, when subjects contrast the mechanical and/or physiological effects of surgical intervention by eating frequently and rapidly, drinking after eating, consuming large amounts of condiments or calorie-rich beverages or by “grazing,” cumulative energy intake is not modified, resulting in reduced weight loss and/or weight gain. Thanks to the permanent and selective limitation of intestinal absorption of energy-rich substrates, body weight of those subjects having undergone biliopancreatic diversion is nearly completely independent of food consumption. Therefore, permanent changes in eating habits and behaviors are not necessary in order to achieve satisfactory weight loss and maintenance, which can be obtained with a completely “free” diet in the vast majority of cases. After biliopancreatic diversion, a marked improvement in eating behavior is observed, with an overall reduction in the prevalence of binge eating episodes and a sharp decrease in disinhibitive and cognitive restraint. Some studies have demonstrated that weight loss obtained via the gastric restriction procedure is accompanied by general improvement in eating behaviors, while other research has shown that after surgical intervention a high disinhibition level is maintained, usually accompanied by poor weight loss and increased weight regain. Prior to gastric restriction procedures or biliopancreatic diversion, psychological and/or behavioral preoperative factors have not proven effective in predicting weight outcome in the presence of postoperative complications, and behavioral intervention prior to surgical intervention does not improve clinical results. After biliopancreatic diversion, the vast majority of subjects succeed without therapy in adapting both to the new anatomical and functional gastrointestinal tract conditions derived from the intervention as well as to the novel somatic morphology resulting from stable weight loss. Only a small minority of patients require standard behavioral modification treatment to improve their individual quality of life. On the contrary, for the purpose of achieving satisfactory weight outcomes for a greater possible number of subjects having undergone gastric banding, gastroplasty, and gastric bypass, specific behavioral intervention aimed at improving individual eating habits and behaviors, adapted to gastric restriction, must be envisaged. Full recovery from severe obesity includes the steady reduction of body weight in keeping with the physiological range, as well as the disappearance of comorbidities specifically caused by obesity, such as impaired glucose tolerance, type 2 diabetes, blood hypertension, and dyslipidemia Generally, conservative therapy does not succeed in obtaining these results: reducing diet and eating behavior modification may lead to minor weight loss, with a concomitant benefit on comorbidities: however, weight regain within a few months with the reappearance of complications is unfortunately the rule in nearly all cases. Modern pharmacologic therapy results only in a 10% decrease in body weight. Moreover, the chronic use of antiobesity drugs can lead to severe side effects, which force the discontinuation of therapy with consequent weight regain. By contrast, bariatric (from the ancient Greek word barus meaning heavy) surgery produces adequate weight loss, which is satisfactorily sustained in the long term along with the stable disappearance or marked improvement in metabolic and structural complications related to obesity (Buchwald et al. 2004). At present bariatric surgery represents the best therapeutic approach to the treatment of severe obesity. Because the prevalence of severe obesity is dramatically increasing in western developed countries), an even greater number of patients undergo surgery for obesity. Therefore, the need for clinicians involved in psychological and behavioral problems related to postobese individuals who have undergone bariatric procedures will undoubtedly increase in the near future. As is generally well known, body weight represents a balance between the individual’s bioenergetic entity and the environment, and any change in body weight is a result of changes in energy intake, energy expenditure, or both (Garrow 1988). Because significant modifications in energy expenditure are inconceivable, bariatric surgery strongly affects energy intake (directly and/or indirectly), then food consumption, with the obvious resulting influence on the individual’s eating habits. For a full understanding of the relationship between eating behavior and obesity surgery, as well as the modifications in eating behavior caused by obesity surgery itself, sufficient knowledge of the principle acting mechanisms of the different bariatric procedures is mandatory.