How walnut versus pretzel snacks change brain responses and fullness during dieting

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

NA · University of Colorado, Denver · NCT07428187

This trial will test whether eating a daily walnut snack versus a pretzel snack changes brain responses to food and feelings of fullness in adults aged 25–45 with BMI ≥27 who are trying to lose weight.

Quick facts

PhaseNA
Study typeInterventional
Enrollment70 (estimated)
Ages25 Years to 45 Years
SexAll
SponsorUniversity of Colorado, Denver (other)
Locations1 site (Aurora, Colorado)
Trial IDNCT07428187 on ClinicalTrials.gov

What this trial studies

Adults with overweight or obesity will join a supervised weight-loss program and be assigned to consume a daily snack of either walnuts or pretzels. The study will track how those different snack types affect brain responses related to eating and measures of satiety and food-related behavior over the course of the diet. Data will come from behavioral measures, self-reported hunger/fullness, and brain-response measurements during food-related tasks. The trial is conducted at the University of Colorado Anschutz Medical Campus in collaboration with the California Walnut Commission.

Who should consider this trial

Good fit: Ideal candidates are adults 25–45 years old with BMI ≥27 who are comfortable participating in a weight-loss program and are willing to eat a daily snack of either walnuts or pretzels.

Not a fit: People with nut or wheat allergies, recent bariatric surgery, current eating disorders, pregnancy or recent postpartum/lactation, uncontrolled hypertension, significant metabolic or organ disease, recent weight-loss medication or steroid use, or recent major mental health changes are excluded and would not benefit from participation.

Why it matters

Potential benefit: If successful, the results could help identify snack choices that reduce cravings and improve feelings of fullness during dieting.

How similar studies have performed: Previous research has shown nuts can increase satiety and have favorable metabolic effects, but direct comparisons of walnuts versus pretzels on brain responses during dieting are limited and relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Aurora, Colorado

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Overweight/Obesity, Dieting, Weight loss, Overweight, Obesity, Food, Neuroimaging, Body weight

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.