The mechanism of weight loss with laparoscopic adjustable gastric banding: induction of satiety not restriction

Abstract

Laparoscopic adjustable gastric banding (LAGB) has rapidly emerged as a popular bariatric procedure because of its safety, efficacy, durability and adjustability. Despite widespread use, there is limited understanding of how it induces weight loss. Previously, it has been classified as a restrictive procedure, physically limiting the patient to a small meal that subsequently slowly empties into the distal stomach. However, the tiny pouch of stomach created above the LAGB appears to be unable to accommodate even the smallest of meals. Therefore, the key mechanism has been hypothesized to be the induction of satiety via, as yet, undefined pathways. The critical question remains: what are the key physiological changes that lead to satiety and weight loss? In successful LAGB patients, a consistent intraluminal pressure at the level of the LAGB of 26.9±19.8 mm Hg is observed. Studies using semi-solid swallows combined with intraluminal pressure recordings have demonstrated that semi-solid transit across the resistance of the LAGB is mediated by repeated esophageal peristaltic contractions (mean 4.5±2.9) that produce episodic flow, interspersed by reflux events. Failed transit results in obstruction and regurgitation, whereas dilatation of the supraband stomach induces severe and intolerable reflux. Overall gastric emptying does not appear to be significantly altered following LAGB. Focused investigations have shown that the supraband stomach is empty of an ingested meal 1-2 min after intake ceases. Considerable progress has been made in understanding the mechanical physiological effects of the LAGB on esophageal and proximal gastric function. These have been correlated with patient outcomes and sensations. On the basis of recent data, it appears that the LAGB activates the peripheral satiety mechanism without physically restricting the meal size. Therefore, it should not be classified as a restrictive procedure. The precise mechanism of weight loss with the LAGB remains to be delineated.

Dilatation of Sleeve Gastrectomy: Myth or Reality?

“…Surprisingly, despite different gastric volumes between the groups, we did not observe any difference concerning daily caloric intake at any point of the follow-up in the subjects with or without sleeve dilatation. Burton et al already reported that weight loss after surgery was mainly due to satiety and not to food restriction [14]. These results are also in accordance with the study of Gras-Miralles et al which showed that caloric intake capacity was similarly reduced after RYGBP and LSG, despite a smaller gastric pouch in RYGBP (30 vs 150 ml) [15].…”

Airway management concerns in patient with gastric banding procedures

“…How the LAGB induces weight loss is not fully understood 4. Initially, weight loss was attributed to eating in small proportions since the pouch fills rapidly and passage to the distal stomach is limited 4 5.…”

“…Initially, weight loss was attributed to eating in small proportions since the pouch fills rapidly and passage to the distal stomach is limited 4 5. Although unable to identify specific changes, Dixon et al 6 emphasised that the band compresses the cardia, altering neuronal and hormonal-induced satiety and decreasing appetite.…”

Bringing Homeostasis Back into Weight Control

“…One way is passive, in other words, when the stomach fills and hunger hormone levels drop, hunger decreases and satiety is experienced as the absence of hunger [38]. Another way is through the stretching of the stomach neurons as the stomach gets full [39]. Stomach muscles stretch triggering afferent neurons that then send signals to the brain to [39].…”

“…Another way is through the stretching of the stomach neurons as the stomach gets full [39]. Stomach muscles stretch triggering afferent neurons that then send signals to the brain to [39].…”