Weight Loss by Low-Calorie Diet Versus Gastric Bypass Surgery in People With Diabetes Results in Divergent Brain Activation Patterns: A Functional MRI Study
posted on 2021-06-22, 18:25authored byVictoria Salem, Lysia Demetriou, Preeshila Behary, Kleopatra Alexiadou, Samantha Scholtz, George Tharakan, Alexander D. Miras, Sanjay Purkayastha, Ahmed R. Ahmed, Stephen R. Bloom, Matthew B. Wall, Waljit S. Dhillo, Tricia M-M. Tan
Objective:
Weight
loss achieved with very low-calorie diets (VLCD) 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 hypothesised that in patients living with
obesity and pre-diabetes/T2D, longitudinal changes in brain activity in
response to food cues as measured using functional MRI would explain this
difference. Methods: 16 participants underwent gastric bypass surgery
and 19 matched participants undertook a very low calorie (meal replacement)
diet for 4 weeks. Brain responses to food cues and resting state functional
connectivity was assessed with functional MRI pre- and post-intervention and
compared across groups. Results: We show that RYGB results in three
divergent brain responses in comparison to VLCD-induced weight loss: (i) VLCD
resulted in increased brain reward centre food cue responsiveness whereas in
RYGB this was reduced; (ii) 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; (iii) a
homeostatic appetitive system (centred on the hypothalamus) is better engaged
following RYGB-induced weight loss than VLCD. Conclusion: 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 with the enduring weight loss after RYGB.
Funding
The study was funded by the MRC Experimental Challenge Grant (MR/K02115X/1) and other aspects of the study were supported by the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre (BRC) Funding Scheme. V.S. is the recipient of a Diabetes UK Harry Keen Clinician Scientist Fellowship. W.S.D. is funded by an NIHR Professorship (RP-2014–05–001). T.M-M.T. is funded by the NIHR and the JP Moulton Charitable Foundation. The research study was also supported by the Imperial NIHR Clinical Research Facility. The Department of Metabolism, Digestion and Reproduction is funded by grants from the MRC and Biotechnology and Biological Sciences Research Council and is supported by the NIHR Imperial BRC Funding Scheme. The views expressed are those of the authors and not necessarily those of the abovementioned funders, the UK National Health Service (NHS), the NIHR, or the UK Department of Health.