A groundbreaking long-term MRI study demonstrates that lower accumulation of abdominal fat (visceral fat), measured throughout the entire follow-up period, is associated with a significant slowing of brain atrophy, preservation of key brain structures, and better cognitive performance in late midlife – independent of weight loss. The findings suggest that the relationship between abdominal fat and brain aging is likely mediated primarily through glucose control and insulin sensitivity. The study is the first to link repeated MRI-based measurements of cumulative visceral fat with long-term trajectories of brain aging and cognition.