Snacking Effects on the Brain Response to Foods and Satiety During Dieting

This study plans to learn more about how different types of snacks may affect brain processes relating to eating behaviors during a diet intervention.

Study Overview

• Status: Recruiting
• Conditions: Overweight/Obesity
• Intervention / Treatment: Other: Snack Type 1: Walnuts; Other: Snack Type 2: Pretzels

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Allison Hild, BS; Phone Number: 3037249024; Email: allison.hild@cuanschutz.edu
• Study Contact Backup: Name: Kristina T Legget, PhD; Phone Number: 303-724-5809; Email: kristina.legget@cuanschutz.edu

Study Locations

• United States
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Recruiting
      • University of Colorado Anschutz Medical Campus
      • Contact: Kristina Legget, PhD; Phone Number: 303-724-5809; Email: kristina.legget@cuanschutz.edu
      • Contact: Allison Hild, BS; Phone Number: 303-724-9024; Email: allison.hild@cuanschutz.edu
      • Principal Investigator: Kristina T Legget, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 25-45 years old
• BMI at least 27 kg/m2
• Comfortable completing a weight-loss intervention\
• Willing to consume a daily snack of either walnuts or pretzels

Exclusion Criteria:

• Nut or wheat allergy
• History of bariatric surgery
• Current eating disorder
• Current illicit substance use
• Current pregnancy, lactation (or less than 3 months after stopping lactation), or less than 6 months postpartum
• Uncontrolled hypertension (>160/100 mmHg)
• Significant endocrine/metabolic disease kidney disease, liver disease, or blood disease that would be anticipated to affect study results
• Taking injectable medications, sulfonylureas, or meglitinides for diabetes treatment
• Taking weight-loss medications, or steroids within ~3 months prior to study participation (e.g., GLP-1 receptor agonists)
• Significant mental health changes within ~3 months prior to study participation (e.g., medication adjustments, new psychiatric diagnoses, hospitalization relating to mental health concerns)
• Neurological illnesses or injury that would be anticipated to affect MRI data
• Weight change greater than 10% within 3 months prior to study participation
• Currently participating in another weight-loss study
• Not comfortable eating the study-provided meals (with allowances for dietary preferences) and/or following a highly restrictive diet (e.g., vegan)
• MRI-specific exclusion criteria (e.g., metal in the body, weight >500 lbs

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Snack Type 1: Walnuts; 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).	Other: Snack Type 1: Walnuts; 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.
Active Comparator: Snack Type 2: Pretzels; 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).	Other: Snack Type 2: Pretzels; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent change in Blood Oxygen Level Dependent (BOLD) response to visual food cues as measured by functional magnetic resonance imaging	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.	Baseline, 12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in percent body fat	Change in percent body fat from baseline to after the 12-week intervention.	Baseline, 12 weeks
Change in appetite response to a meal	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.	Baseline, 12 weeks
Change in food cravings	Change in food cravings (using the Food Cravings Questionnaire) from baseline to after the 12-week intervention	Baseline, 12 weeks
Change in dietary restraint	Change in dietary restraint (measured using the dietary restraint subscale of the Three Factor Eating Questionnaire) from baseline to after the 12-week intervention.	Baseline, 12 weeks
Change in reward-based eating drive	Change in reward based eating drive (measured using the Reward-Based Eating Drive-13 questionnaire) from baseline to after the 12-week intervention.	Baseline, 12 weeks
Change in waist circumference	Change in waist circumference (cm) from baseline to after the 12-week intervention	Baseline, 12 weeks
Change in body weight	Change in body weight (kg) from baseline to after the 12-week intervention	Baseline, 12 weeks

Collaborators and Investigators

• Sponsor: University of Colorado, Denver
• Collaborators: California Walnut Commission
• Investigators: Principal Investigator: Kristina T Legget, PhD, University of Colorado, Denver

Study record dates

Study Major Dates

• Study Start (Actual): March 5, 2026
• Primary Completion (Estimated): March 31, 2028
• Study Completion (Estimated): March 31, 2028

Study Registration Dates

• First Submitted: February 12, 2026
• First Submitted That Met QC Criteria: February 19, 2026
• First Posted (Actual): February 23, 2026

Study Record Updates

• Last Update Posted (Actual): March 23, 2026
• Last Update Submitted That Met QC Criteria: March 19, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Obesity; Overweight; Magnetic resonance imaging; Weight loss; Brain; Neuroimaging; Body weight; Food; Eating; Dieting
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight Changes; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Overweight; Obesity; Weight Loss; Body Weight
• Other Study ID Numbers: 25-1900

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No