Obesity if known to be associated with brain insulin resistance in humans. This condition has not only implication for the brain but also for whole-body energy homeostasis. Research in rodents indicates that weight loss is able to improve insulin sensitivity of the brain. The current project will test this hypothesis in humans. Therefore, brain insulin sensitivity will be assessed by fMRI in combination with intranasal insulin administration, using an established protocol. Furthermore, effects of daily administration of insulin nasal spray (versus placebo) over 8 weeks will be assessed as secondary (exploratory) variables.