Much of the world regularly consumes energy-dense, ultra-processed foods rich in saturated fat and sugar. In addition to increasing risk of obesity and other chronic disease, this dietary pattern is associated with cognitive impairment and poorer brain health. What is less well know is whether these cognitive effects persist or recover once the unhealthy diet is replaced with a healthy one; i.e., diet reversal. Understanding the effects of diet reversal is relevant in light of the common tendency for people to alternate between healthy and unhealthy diets, and given widespread use of GLP-1 receptor agonists to control appetite and food choice. In this talk I will present recent work from my group and others interrogating the effects of diet reversal on neurocognitive health, metabolic measures, and gut microbiome composition. Our meta-analysis of preclinical models reveals domain-specific effects of diet reversal, with partial recovery of memory function. I will discuss how changes in cognition are associated with metabolic and microbiome changes, and present data showing sex-specific neural effects of diet reversal in an animal model.