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RecruitingNCT07428187Updated Mar 23, 2026

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

An interventional study of Snack Type 1: Walnuts and Snack Type 2: Pretzels in Overweight/Obesity, sponsored by University of Colorado, Denver. Recruiting at 1 site in United States. Open to participants aged 25 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-03-23.

Sponsored by University of Colorado, Denver · Not applicable, Interventional, and Other

Phase
Not applicable
Study type
Interventional
Enrollment
70
Allocation
Randomized
Ages
25 Years to 45 Years
Sex
All
01

Study summary

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

02

Conditions studied

  • Overweight/Obesity

Keywords

  • Dieting
  • Weight loss
  • Overweight
  • Obesity
  • Food
  • Neuroimaging
  • Body weight
  • Eating
  • Brain
  • Magnetic resonance imaging
03

Who can participate

Ages eligible
25 Years to 45 Years
Sexes eligible
All
Accepts healthy volunteers
No

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

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
04

Study design

Phase
Not applicable
Primary purpose
Other
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Investigator, Outcomes assessor)
Enrollment
70 participants (estimated)

Study arms

  • 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

  • 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

Interventions

  • OtherSnack 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.

  • OtherSnack 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.

05

What researchers measure

Primary outcomes

  1. 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.

    Time frame: Baseline, 12 weeks

Secondary outcomes

  1. Change in percent body fat

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

    Time frame: Baseline, 12 weeks

  2. 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.

    Time frame: Baseline, 12 weeks

  3. Change in food cravings

    Change in food cravings (using the Food Cravings Questionnaire) from baseline to after the 12-week intervention

    Time frame: Baseline, 12 weeks

  4. 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.

    Time frame: Baseline, 12 weeks

  5. 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.

    Time frame: Baseline, 12 weeks

  6. Change in waist circumference

    Change in waist circumference (cm) from baseline to after the 12-week intervention

    Time frame: Baseline, 12 weeks

  7. Change in body weight

    Change in body weight (kg) from baseline to after the 12-week intervention

    Time frame: Baseline, 12 weeks

06

Study locations

1 of 1 sites recruiting
  • University of Colorado Anschutz Medical Campus
    Aurora, Colorado 80045, United States
    Recruiting
07

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

08

Registry details

Key details

Study ID
NCT07428187
Lead sponsor
University of Colorado, Denver
Collaborators
California Walnut Commission
Responsible party
Sponsor
First posted
Feb 23, 2026
Start date
Mar 5, 2026
Primary completion
Mar 31, 2028 (estimated)
Completion
Mar 31, 2028 (estimated)
Last update
Mar 23, 2026

Study contacts

Allison Hild, BS
Contact
allison.hild@cuanschutz.edu
3037249024
Kristina T Legget, PhD
Contact
kristina.legget@cuanschutz.edu
303-724-5809
Kristina T Legget, PhD
principal investigator · University of Colorado, Denver

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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