Grant: Team Grant: Health Effects of Ultra-Processed Foods-Mechanisms of Health Eff-LOI

Ultra-processed foods now make up the largest share of calories consumed in Canada and around the world. Diets high in these foods are consistently linked to obesity, diabetes, heart disease, and problems with brain health, yet we still do not understand why ultra-processed foods are so easy to overeat. This lack of understanding makes it difficult to design effective public health policies, improve food products, or help people make healthier choices. This research program tests a new idea called the Absorption Hypothesis. Rather than focusing only on calories, sugar, fat, or taste, we propose that ultra-processed foods are harmful because they are eaten and digested very quickly. Food processing breaks down natural food structure, allowing nutrients to be absorbed rapidly in the gut. Faster nutrient absorption weakens feelings of fullness while generating stronger reward signals in the brain. Over time, these signals "train" the brain to seek out ultra-processed foods, even when the body does not need energy, leading to habitual and sometimes compulsive eating. To test this idea, we will combine studies in people with experiments in animal models. In humans, we will use advanced brain imaging to measure how quickly nutrients trigger dopamine release, a chemical involved in motivation and learning, and how this shapes eating behavior. We will also study large population datasets to determine whether diets that deliver nutrients more rapidly are linked to poorer metabolic health, brain injury, and cognitive decline. Animal studies will allow us to directly test cause-and-effect relationships that cannot be examined in people. By identifying which features of ultra-processed foods drive rapid absorption and overeating, this research will provide evidence needed to guide food reformulation, labeling, and public health policy. Ultimately, the goal is to move beyond blaming individuals and toward creating food environments that support healthier brains and bodies.