Food preferences and underlying mechanisms after bariatric surgery

Abstract

Bariatric surgery leads to significant long-term weight loss, particularly Roux-en-Y gastric bypass (RYGB). The mechanisms underlying weight loss have not been fully uncovered. The aim of this review is to explore the changes in food preferences, as a novel mechanism contributing to weight loss, and also focus on the underlying processes modulating eating behaviour after bariatric surgery. Patients after gastric bypass are less hungry and prefer healthier food options. They develop an increased acuity to sweet taste, which is perceived as more intense. The appeal of sweet fatty food decreases, with functional MRI studies showing a corresponding reduction in activation of the brain reward centres to high-energy food cues. Patients experiencing post-ingestive symptoms with sweet and fatty food develop conditioned aversive behaviours towards the triggers. Gut hormones are elevated in RYGB and have the potential to influence the taste system and food hedonics. Current evidence supports a beneficial switch in food preferences after RYGB. Changes within the sensory and reward domain of taste and the development of post-ingestive symptoms appear to be implicated. Gut hormones may be the mediators of these alterations and therefore exploiting this property might prove beneficial for designing future obesity treatment.

Taste of Fat: A Sixth Taste Modality?

“…A profound change in the spontaneous eating habits leading to healthier food options usually occurs after bariatric surgery. Consistent with the neurovulnerability hypothesis, fMRI studies before and after surgery have revealed a reduction in activation of the "emotional brain" after weight loss (8). To further assess the impact of bariatric surgery on appetitive value of foods, Carel le Roux and his colleagues from the Imperial College of London (UK) have submitted fasted lean and obese volunteers to a reward protocol that consisted of clicking 10 times on a computer mouse to obtain a chocolate candy or vegetable pieces, the number of clicks being twofold increased after each reward.…”

Increased intravenous morphine self-administration following Roux-en-Y gastric bypass in dietary obese rats

“…In fact, rats with free access to HFD display impaired acquisition of cocaine self-administration (Wellman et al, 2007) and amphetamine-conditioned place preference (Davis et al, 2008). Thus, one may suppose that the reduced consumption of fatty foods following the surgery (Behary and Miras, 2015) may reverse blunted reward and drug seeking. Recent brain imaging studies suggest that following RYGB, food-cues may elicit reduced activation in brain (Ochner et al, 2011; Ochner et al, 2012a; Ochner et al, 2012b; Scholtz et al, 2014).…”

The gut in the brain: the effects of bariatric surgery on alcohol consumption

“…Consistent with this study, an additional study that measured brain-glucose metabolism indicated activation of brain areas involved in reward expectation and sensory processing during anticipation of a palatable fatty food (Thanos et al 2015). Thus, it appears that while the surgery ultimately reduces intake of rich (very sweet and fatty) foods, an effect reliably demonstrated both in humans and animals (Behary & Miras 2015; Brown et al 1982; Halmi et al 1981; Le Roux et al 2011; Olbers et al 2006), the brain areas activating anticipatory responses to rewarding cues remain on ‘high alert’. In fact, recent studies investigating taste functions and taste reward supports this notion, and suggests that reduced sweet and fat preferences following RYGB surgery are rather due to learned aversions to certain foods, than a primarily reduced reward function (Mathes et al 2015a; Mathes et al 2015b; Mathes et al 2012).…”