Impact of bariatric surgery on neural food processing and cognition: an fMRI study

Weight Loss by Low-Calorie Diet Versus Gastric Bypass Surgery in People With Diabetes Results in Divergent Brain Activation Patterns: A Functional MRI Study

OBJECTIVE

Weight loss achieved with very-low-calorie diets (VLCDs) can produce remission of type 2 diabetes (T2D), but weight regain very often occurs with reintroduction of higher calorie intakes. In contrast, bariatric surgery produces clinically significant and durable weight loss, with diabetes remission that translates into reductions in mortality. We hypothesized that in patients living with obesity and prediabetes/T2D, longitudinal changes in brain activity in response to food cues as measured using functional MRI would explain this difference.

RESEARCH DESIGN AND METHODS

Sixteen participants underwent gastric bypass surgery, and 19 matched participants undertook a VLCD (meal replacement) for 4 weeks. Brain responses to food cues and resting-state functional connectivity were assessed with functional MRI pre- and postintervention and compared across groups.

RESULTS

We show that Roux-en-Y gastric bypass surgery (RYGB) results in three divergent brain responses compared with VLCD-induced weight loss: 1) VLCD resulted in increased brain reward center food cue responsiveness, whereas in RYGB, this was reduced; 2) VLCD resulted in higher neural activation of cognitive control regions in response to food cues associated with exercising increased cognitive restraint over eating, whereas RYGB did not; and 3) a homeostatic appetitive system (centered on the hypothalamus) is better engaged following RYGB-induced weight loss than VLCD.

CONCLUSIONS

Taken together, these findings point to divergent brain responses to different methods of weight loss in patients with diabetes, which may explain weight regain after a short-term VLCD in contrast to enduring weight loss after RYGB.

Is weight regain after bariatric surgery associated with psychiatric comorbidity? A systematic review and meta-analysis

Bariatric surgery has been recognized as the gold standard treatment for severe obesity. Although postbariatric surgery patients usually achieve and maintain substantial weight loss, a group of individuals may exhibit weight regain. Several factors are proposed to weight regain, including psychiatric comorbidity. The objective of the study is to conduct a systematic review and meta-analysis of studies investigating the relationship between psychiatric comorbidity and weight regain. A systematic review through PubMed, Web of Science, Cochrane Library, Scopus, and PsycINFO was performed, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). After a stepwise selection, 13 articles were included in the qualitative analysis and 5 were included for a meta-analysis. Women was majority in most of the studies (87.6%), and a bypass procedure was the bariatric intervention most evaluated (66.8%), followed by gastric banding (32.1%) and sleeve (1.1%). Higher rates of postbariatric surgery eating psychopathology were reported in patients with weight regain. However, the association between general psychopathology and weight regain was not consistent across the studies. In the meta-analysis, the odds of eating psychopathology in the weight regain group was higher compared with the nonweight regain group (OR = 2.2, 95% CI 1.54-3.15). Postbariatric surgery eating psychopathology seems to play an important role in weight regain.