Obesity is a significant risk factor for cerebrovascular disease including dementia. Cerebral blood flow (CBF) provides a biomarker of cerebrovascular health and can be measured non-invasively using arterial spin labeled (ASL) perfusion MRI. Here we examined longitudinal ASL data from adult women with obesity who underwent bariatric surgery. We demonstrated that weight loss was associated with significant increases in CBF from baseline to 6 and 18 months after surgery. Change in glucose and insulin level did not mediate the relationship, suggesting a more direct association between obesity and CBF.