Purpose <p>Increased adiposity is associated with the development of cardiometabolic disturbances, with sympathetic dysregulation playing a crucial role in the early phase. Both adiposity and chronic sympathetic activation may impair cerebral function, increasing the risk of neurodegenerative diseases. However, whether adiposity and sympathetic activity are associated with brain dynamics in the healthy state is not fully understood.</p> Methods <p>We performed magnetoencephalography in 29 healthy participants (12 males and 17 females; age 19–72 years; body fat percentage 7–45.3%) to record brain dynamics as neural activity index and functional connectivity. Adiposity was assessed using body fat percentage and microneurography was used to assess muscle sympathetic nerve activity.</p> Results <p>Individuals with higher fat percentage had higher muscle sympathetic nerve activity. Group comparison showed lower activity in the left posterior cingulate gyrus (delta and theta bands) and left precuneus (delta band) in individuals with higher fat percentage. Stronger connectivity between the right superior frontal gyrus and left temporal pole (delta band) was also seen in this group. Neural activity index in the right caudate (theta and low-gamma bands) correlated positively with muscle sympathetic nerve activity while correlating negatively with body fat percentage.</p> Conclusion <p>We have shown that resting-state brain activity and functional connectivity are associated with adiposity and sympathetic activity even in healthy individuals with no manifest cardiometabolic diseases. Thus, the findings highlight that understanding central pathways associated with the healthy state may help to uncover the pathophysiology of obesity and associated metabolic disorders.</p>