The Impact of Preoperative Eating Patterns on Weight Loss Outcomes After Different Types of Bariatric Surgery

Bariatric surgery techniques: an overview

Restrictive bariatric procedures promote weight loss by making changes to stomach capacity, thus reducing the amount of food that can be eaten at a particular time, yet not modifying other portions of the digestive tract. ⁷ The two leading forms of restrictive surgery are sleeve gastrectomy and gastric band. In sleeve gastrectomy, 80% of the stomach is surgically removed whereas in gastric band, an inflatable band is placed around the upper portion of the stomach.

Roux-en-Y gastric bypass (RYGBP) combines both restrictive and malabsorptive elements. The restrictive element consists in stapling the stomach into two portions—the “new” stomach corresponds to the upper smaller part. The malabsorptive component refers to the anastomosis between the new stomach and the lower part of the small intestine, bypassing the upper portion of the small intestine where food absorption normally takes place. ¹

Preoperative weight loss and surgical outcomes

The relationship between preoperative weight loss and medium- and/or long-term postoperative outcomes remains unclear. A further confusing factor is that the results of several studies are dependent on the occurrence or not of certain circumstances, such as the type of surgery (restrictive vs. malabsorptive techniques), and specific eating behaviors. ⁸

For a better comprehension of research results, certain parameters and terms should be defined ⁴ : \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*} { \rm{Excess \ body \ weight }} \ \left( {{ \rm{EBW}}} \right) { \rm{ = Actual \ weight - Ideal \ weight}} \end{align*} \end{document} \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*} { \rm{ \% }} \ { \rm{Excess \ weight \ loss }} \ \left( {{ \rm{ \% EWL}}} \right) { \rm{ = [ ( Operative \ weight - Follow{ -}up \ Weight ) / Operative \ EBW ] }} \times 100. \end{align*} \end{document}

A recent prospective study using those parameters in 50 morbid obese patients demonstrated that a preoperative weight loss greater than 15% of EBW was positively associated with better %EWL outcomes at 12 months (93.9% vs. 81.6%, p = 0.014) and 24 months (94.1% vs. 84.5%, p = 0.002) after sleeve gastrectomy. ⁴

In contrast, no association between preoperative weight loss and postsurgical %EWL was found by another prospective study that analyzed 95 patients who underwent laparoscopic RYGB and sleeve gastrectomy, within a follow-up period of 4 years. ⁹ All participants had nutrition advice, aiming at 5–10% EWL before bariatric surgery. The authors reinforce the contradictory results reported by other investigators. Even then, they keep on encouraging a preoperative weight loss educational program, mainly because preoperative habit changes may improve the patient's ability to adapt to the drastic reduction in the gastric volume, helping them to choose the most suitable types of food and timing of ingestion. ⁹ Additional health benefits, such as decrease of surgical time, improvement of comorbidities, and liver mass reduction, have been well recognized in patients who lost 5–10% of body weight before bariatric surgery. ⁶

A recent robust systematic review that assessed the available data on presurgical predictors of weight loss following bariatric surgery was not conclusive with regard to the impact of preoperative weight loss on postsurgical outcomes. ³ The authors reported a significant positive association between mandatory presurgical weight loss and a considerable postoperative weight loss (greater than 50% EWL) in only 7 out of 14 studies. They were included in this review, a total of 115 studies, which analyzed not only preoperative weight loss, but also other postulated predictors of postoperative weight loss, including BMI and personality disorders, which were demonstrated to negatively influence the surgical outcomes, in terms of weight loss. ³

The relationship between eating patterns and postoperative outcomes

A wide variety of eating behaviors and eating disorders are reported in candidates before bariatric surgery.^4,5,8,10 Mitchell et al. demonstrated that, among bariatric patients, 8% used to skip dinner, and 46%, breakfast. ⁹ Fifty percent of the participants took at least four meals per week at restaurants, half of those meals at fast food stores. Nocturnal eating disorder was reported in about 18% of them, whereas 2% suffered from bulimia nervosa. ⁹ According to the authors, BED was diagnosed in 16% of their population. Its prevalence was reported higher among college students, grazers, and psychiatric patients, including those with alcohol use disorder and major depression. ¹⁰

Ruiz-Tovar et al. conducted a prospective study consisting of 50 morbid obese patients, who underwent sleeve gastrectomy in the period between 2008 and 2012, aiming to investigate the effects of recognized preoperative eating patterns on the short- and midterm surgical outcomes. ⁴ Among the participants, 48% reported regular ingestion of soft drinks (regular intake of soda during and out of meals), 44% were classified as “snackers” (continued intake of small amounts of food), and 40% were sweet-eaters (daily consumption of sugary foods). The results showed that the mean postoperative EWL at 12 and 24 months after sleeve gastrectomy was significantly lower in those who presented with the investigated eating behaviors, as shown in Table 1, thus leading to the conclusion that such specific population achieves worse outcomes in terms of weight loss, following sleeve gastrectomy. ⁴

Such findings were in accordance with Sugerman, ¹¹ who demonstrated that sweet-eaters who underwent vertical gastroplasty presented a significantly lower weight loss in comparison with non-sweet-eaters, following surgery (p < 0.05). On the contrary, in individuals submitted to RYGBP, no significant differences in weight loss were observed between sweet-eaters and non-sweet-eaters. ¹¹ According to this study, gastric bypass intervention leads to significantly better outcomes in sweet-eaters, when comparing short- and long-term %EWL between the RYGBP and vertical gastroplasty groups (p < 0.0001). Table 2 summarizes the results.

Possible explanations for the comparable results found by Ruiz-Tovar et al. ⁴ and Sugerman ¹¹ are as follows:

(1) The “snacker” behavior is less affected by gastric restriction due to the smaller quantities of food continually consumed; ¹²

Other mechanisms involved in the weight gain or failure to lose weight secondary to soft drinks regular intake include the increase in caloric intake, appetite stimulation, and replacement of milk and other healthy foods. ¹³ Moreover, abrupt changes in blood glucose and insulin levels following the ingestion of sweets or sugary beverages increase the appetite, due to the rapid absorption of high glycemic carbohydrates. ¹³

Another interesting investigation demonstrated that preoperative grazing pattern, defined as the continuous intake of small amounts of food along the day, was highly likely to persist after bariatric surgery, in a rate of 94.1%. ¹⁴ Corroborating other investigators, this study showed that persistent grazing after laparoscopic adjustable gastric banding was associated with more symptoms of depression (p = 0.033) and worse outcomes in comparison to the average, as demonstrated by the percentage of weight loss (15.7% ± 7.8% vs. 20.8% ± 8.5%) and %EWL (37.3% ± 19.0% vs. 50.0% ± 20.7%) (p < 0.001). ¹⁴

On the contrary, two recent cohort retrospective studies failed to demonstrate a correlation between different eating habits, including the “sweet-eaters”, and the short- and midterm outcomes after restrictive interventions.^15,16 Contrary to the formerly concept, in which gastric bypass procedures were considered more suitable to obese sweet-eaters, relying on the fact that such patients could quit from excess sweet consumption due to the unpleasant symptoms of dumping syndrome, these authors defend that the long-term success of bariatric surgery depends mostly on a multidisciplinary support and strategies to maintain patients on a healthier lifestyle, rather than on the surgical technique. ¹⁶

Another relevant point to be assessed concerns to changes in the preference for food often observed after bariatric surgery, as demonstrated in a very recent study that evaluated the impact of eating preferences on weight loss of 41 morbid obese patients who underwent RYGBP (median %EWL = 63.5%, 6 months after surgery). ¹⁷ The results reveal a favorable trend that suggests an increasing replacement of “fast food” for healthier options. Hamburger and pizza consumption rates decreased from 18% to 15.4% before surgery, to zero and 5.1%, respectively, 6 months after surgery. In contrast, fish and plain yogurt consumption, which was zero before gastric bypass, increased to 5.1% and 25.6%, respectively. In this study, the most observed behavioral effect following RYGBP was the reduced intake of sweets and fatty foods. ¹⁷ The authors postulated that such modifications in food preference may be multifactorial, resulting from the feared symptoms of malabsorptive and dumping syndromes, and the patient involvement in nutritional counseling programs. ¹⁷

The role of the MDT in selecting patients for bariatric surgery

Different members of a MDT play specific roles in the decision of management pathways for each patient. ¹⁸ The bariatric physician is usually the first point of contact when a potential candidate for bariatric surgery is seen in a bariatric center. As the team leader, his role consists in managing the patient in a holistic manner, taking into account the health impact of obesity and coordinating therapeutic measures, in close contact with the specialist dietician, clinical psychologist, nurse, and surgical staff, thus properly addressing the needs of each patient. ¹⁹

Preoperative dietary and psychological consultations are crucial for identifying patients at high-risk eating patterns, that is, those with histories of emotional eating, significant snacking habits, and BED. ¹⁸ Such patients should necessarily receive dietary and psychological counseling to improve maladaptive eating behaviors before surgery. Preoperative diet modifications promote the development of alternative responses to stress, thus weakening the conditioned behavior between emotions and overeating. ¹⁸ Furthermore, presurgical dietary changes introduce bariatric patients to postsurgical recommendations, such as the three daily meals, minimal snacking, the need of breakfast, and withdrawal of high-sugar and high-fat foods. ¹⁹ Despite the efforts, some patients fail to adhere to the postoperative requirements, returning to past unhealthy habits or even developing new pathological behaviors, thus, the need of a diligent attention from the MDT, both pre- and postoperatively. ¹

Another point to be addressed is the need of counseling on how to chew properly. ¹⁹ Many bariatric patients, due to an inadequate mastication, feel discomfort in the passage of certain foods through the gastric outlet, such as fibers and meat. This difficulty often leads to a reduced intake of some nutrients, such as iron, and an increased consumption of fluids and carbohydrates. ¹⁷

According to Saunders, ²⁰ the various overeating patterns should be assessed preoperatively to avoid negative surgical outcomes. In this population, the MDT should focus on the diagnosis and management of the subjective loss of control, rather than on overeating per se.