Reward learning and decision-making processes, which operate largely outside of conscious control, shape food choices and eating behaviors. Excess adiposity is associated with differences in brain structure and functional connectivity underlying these processes, and insulin resistance, which commonly co-occurs with excess adiposity, has been linked with dopamine signaling that is crucial for these processes. However, whether and how excess adiposity and insulin resistance affect reward learning and decision-making remains poorly understood. This study will address that gap, examining the effects of excess adiposity and insulin resistance, and their interaction, on processes of reward learning and decision-making in food-specific and general contexts.

Inclusion Criteria:

• 18 to 45 years of age
• Self-reported weight stable (within 5 lbs) for previous 3 months
• Not pregnant or planning to become pregnant during study participation
• Weigh more than 110 lbs (due to blood draws used in study)
• Residing in Roanoke, VA, area and/or willing to attend sessions at the Fralin Biomedical Research Institute

Exclusion criteria:

• BMI < 18.5 or > 40 kg/m2
• Hemoglobin A1c > 6.4%
• Fasting blood glucose > 126 mg/dL
• 2-hour blood glucose > 200 mg/dL
• Self-reported current diagnosis of diabetes or other endocrine/metabolic disorder
• Self-reported current inhaled nicotine use
• Self-reported history of alcohol dependence
• Self-reported use of medications known to influence study measures (including antiglycemic agents, thyroid medications, etc.)
• Self-reported neurological or psychological disorder
• Self-reported claustrophobia or discomfort with mock fMRI training
• Self-reported history of head injury resulting in loss of consciousness for more than 10 minutes
• Contraindications to MRI, including pacemaker, aneurysm clip, neurostimulator, cochlear implant, metal in eyes, steel worker, other implants
• Self-reported previous metabolic/weight loss surgery
• Self-reported adherence to special or restrictive diet within the past 3 months (e.g., low-carb, ketogenic, exclusion of food groups/specific macronutrients, etc.)
• Self-reported allergy to ingredient used in the study drinks