Changes in neural responsivity to highly palatable foods following roux-en-Y gastric bypass, sleeve gastrectomy, or weight stability: An fMRI study

Abstract

Objective: This prospective, observational fMRI study examined changes over time in blood oxygen level dependent (BOLD) response to high- and low-calorie foods (HCF and LCF) in bariatric surgery candidates and weight-stable controls.

Methods: Twenty-two Roux-en-Y gastric bypass (RYGB) participants, 18 vertical sleeve gastrectomy (VSG) participants, and 19 weight-stable controls with severe obesity underwent fMRI before and 6 months after surgery/baseline. BOLD signal change in response to images of HCF vs. LCF was examined in a priori regions of interest.

Results: RYGB and VSG participants lost 23.6% and 21.1% of initial weight, respectively, at 6 months, and controls gained 1.0%. Liking ratings for HCF decreased significantly in the RYGB and VSG groups but remained stable in the control group. BOLD response in the ventral tegmental area (VTA) to HCF (vs. LCF) declined significantly more at 6 months in RYGB compared to control participants but not in VSG participants. Changes in fasting ghrelin correlated positively with changes in VTA BOLD signal in both RYGB and VSG but not in control participants.

Conclusions: Results implicate the VTA as a critical site for modulating postsurgical changes in liking of highly palatable foods and suggest ghrelin as a potential substrate requiring further investigation.

Figure 1

Mean (±SEM) change in weight (kg) over time (baseline to 6 months). “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants.

Figure 2

Figure 2a. Mean (±SEM) change in liking of high-calorie foods over time. Figure 2b. Mean (±SEM) change in liking of low-calorie foods over time. “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants.

Figure 3

Mean (±SEM) BOLD responses to high-calorie and low-calorie foods at baseline in selected regions of interest (ventral tegmental area [VTA], nucleus accumbens [Nacc], orbitofrontal cortex [OFC], amygdala [Amyg.], anterior cingulate cortex [ACC], insula [Ins.], hippocampus [Hipp.], thalamus [Thal.], prefrontal cortex [PFC], hypothalamus [Hypothal.])

Figure 4

Upper panel: Representative slice showing activation in the ventral tegmental area Lower panel: Mean (± SEM) change in VTA BOLD response to high-calorie foods compared to low-calorie foods at baseline and 6 months. “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants.

Figure 5

Figure 5a. Mean (± SEM) changes in VTA BOLD response to high-calorie foods. “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants. Figure 5b. Mean (± SEM) changes in VTA BOLD response to low-calorie foods. “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants.

Figure 6

Correlations between changes in fasting ghrelin levels (pg/ml) and changes in VTA BOLD response to high-calorie foods minus low-calories foods over time in RYGB (6a), VSG (6b) and control (6c) participants. “RYGB” = Roux-en-Y gastric bypass participants; “Sleeve” = vertical sleeve gastrectomy participants.