Normal Weight

The goal of this clinical trial is to learn how the gut hormone glucagon-like peptide-1 (GLP-1) helps the brain sense sugar. It includes adults with healthy weight and adults with obesity. The main questions this trial aims to answer are: A. Does GLP-1 cause the brain's response to sugar? B. Do lower GLP-1 levels cause a weaker brain response to sugar in adults with obesity? Researchers will compare each participant's brain response across four test days. On these days, GLP-1 levels will be blocked, raised, or left unchanged. Sugar will be given either into the stomach or into a vein. Participants will: Attend 1 screening visit Visit the clinic for 4 test days Receive sugar and get an MRI scan of their brain on each test day

The overarching goal of the current study is to investigate the effect of GLP-1 on brain insulin responsiveness in a randomized, single-blinded, within subject cross-over study design. To this end, investigators will compare the effect of the administration of semaglutide versus placebo, followed by an fMRI with administration of intranasal insulin or placebo.