Hypertension, elevated fasting blood glucose and plasma insulin develop in rats fed a high fat (HF) diet. Our goal was to assess the effects of obesity, beginning in childhood, on the adult cardiovascular system. We hypothesized that rats fed a HF diet would have larger ischemic cerebral infarcts and middle cerebral artery (MCA) remodeling. Three-week-old male Sprague Dawley rats were fed a HF (obese) or control diet for 10 weeks. Cerebral ischemia was induced by MCA occlusion (MCAO). MCA structure was assessed by pressure myography and cerebral vessel matrix metalloproteinase (MMP) activity and expression and collagen levels were measured in vessels from rats that did not undergo MCAO. The cerebral infarct was greater in the obese rats than the control (46.0+/-2.1 vs 28.0+/-7.5% of the hemisphere infarcted, obese vs control p<0.05). The MCAs from obese rats had smaller lumens (232+/-7.2 vs 254+/-7.8 microm obese vs control p<0.05) and thicker walls (19.6+/-0.8 vs 17.8+/-0.9 microm obese vs control p<0.05) and were less compliant than MCAs from control rats. MMP-2 activity and collagen I expression were increased in vessels from obese rats and MMP-13 expression was reduced. These results suggest that obesity, beginning in childhood, causes inward vessel remodeling with a concomitant increase in vessel stiffness due to increased collagen deposition. These changes in MCA structure may be responsible for the increase in the ischemic damage after MCAO.