Participants will complete a 12 week diet intervention, during which they will be asked to reduce their daily caloric intake. During the diet intervention, participants in the Snack Type 1 group will be asked to eat a daily snack of walnuts, which will be provided by the study team. Participants will meet with study staff on a weekly basis during the intervention (with some meetings virtual and in-person visits every 2-3 weeks).

Participants will complete a 12 week diet intervention, during which they will be asked to reduce their daily caloric intake. During the diet intervention, participants in the Snack Type 2 group will be asked to eat a daily snack of pretzels, which will be provided by the study team. Participants will meet with study staff on a weekly basis during the intervention (with some meetings virtual and in-person visits every 2-3 weeks).

Participants will complete a 12 week diet intervention, during which they will be asked to reduce their daily caloric intake. During the diet intervention, participants in the Snack Type 1 group will be asked to eat a daily snack of walnuts, which will be provided by the study team.

Percent change in blood oxygen level dependent (BOLD) response from baseline to after the 12-week intervention while viewing visual food cues will be measured using functional magnetic resonance imaging (fMRI), focusing on insula, striatum, amygdala, and prefrontal cortex.

Change in percent body fat from baseline to after the 12-week intervention.

Change in appetite response to a meal (area under the curve for visual analog scale [VAS] ratings of hunger and satiety across fasted and fed states) from baseline to after the 12-week intervention.