Grant: DRA : Canada Graduate Research Scholarship - Doctoral Program (CGRS D)

Obesity is a long-term disease that raises the risk of heart disease, type 2 diabetes, and many other serious health problems. Around the world, almost 1 billion adults were living with obesity in 2020, and that number is expected to nearly double by 2035. For people with severe obesity, the most effective treatment-when changes in lifestyle and medications are not enough-is metabolic bariatric surgery (MBS). This type of surgery often leads to major weight loss, but results vary from person to person, and we do not fully understand why. Two factors that may help explain these differences are diet and the gut microbiome. The gut microbiome is the community of bacteria and other microorganisms living in the digestive system. Both diet and gut microbes play important roles in controlling weight. Diets that are low in nutrients and fibre are linked to fewer types of gut bacteria, and this loss of diversity is often seen in obesity. Despite this, very few studies have looked at how diet and the gut microbiome work together to affect weight before and after MBS. This study uses MBS as a unique window to study these connections. We recruited 60 adults who are having MBS and 40 adults on the waitlist for MBS. Participants complete health questionnaires, give samples of blood, urine, and stool, and record their daily diets using a mobile app. These steps take place both before surgery and again 12 months later. By studying patterns in diet and gut microbes, we will group patients into clusters and explore how these groups are linked to weight changes over time. This project is part of a $1.5 million study funded by the Weston Family Foundation and conducted at one of Canada's largest MBS clinics. The results will offer new insights into how diet and gut microbes shape recovery and weight outcomes. In the future, this knowledge can guide more personalised care, including specialised diets or probiotics, to improve long-term success after surgery.