20 healthy weight participant (18 Kg/m2>BMI<30Kg/m2) and 20 age- and sex- matched peoples with obesity (BMI >30 Kg/m2) will be invited to a double-blinded two-way crossover MRI study, approximately 1 week apart, to assess the interplay between brain and gut to food intake.~Brain and gut MRI scans will be collected at fasted/baseline and at different time points postprandial for 120 mins using the 3T Ingenia Philips scanner. Brain measurements including resting state-fMRI, cerebral blood flow (CBF), and task-fMRI scans will be collected. During the task fMRI scan, images of high and low energy food pictures, and non-food control pictures will be presented. Food images are extensively used in fMRI studies to characterise the neural systems involved in processing the hedonic value of food as well as satiety and hunger signals. In addition to brain scans, sequences of gut scans will be collected to assess gastric volume, small bowel water content, and superior mesenteric artery (SMA) responses pre- and post-prandial. Blood samples will be collected to assess gut hormones (CCK, GLP1- PYY, ghrelin) insulin and glucose, triglycerides, free fatty acid levels at different timepoints. In addition, satiety and appetite scores will be collected using visual analogue scales. The total scan time including the fed and break times is around 3 hours.
The mechanism of neural communication between the brain and gut in the regulation of food intake is complex and not fully understood. Magnetic Resonance Imaging (MRI) is a powerful non-invasive imaging tool that allows studying the function of the brain and gut. The aim of this study is to develop MRI methods to combine brain and gut imaging in a single MRI scan session. The developed techniques will then be used to assess the brain-gut axis to a high fat drink compared with iso-caloric/iso-viscous/iso-volumetric carbohydrate drink in people with obesity and healthy weight participants. The findings could provide a possible explanation for why some people are heavier than others.