Pistachio Snacking and Metabolic Flexibility

NCT ID: NCT07340125

Last Updated: 2026-01-14

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 60 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-09-01
• Study Completion Date: 2026-12-31

Brief Summary

The purpose of this study is to evaluate the effects of pistachio snacking on metabolic flexibility (at rest, during exercise, and in post-exercise recovery) in healthy overweight and obese adults. Secondary goals include evaluating effects on changes in diet quality, sleep characteristics, physical activity, and hormonal health in women. In randomized order, participants will complete four days of pistachio snacking and four days of normal dietary habits (control). For both conditions, primary outcomes of resting substrate metabolism, metabolic flexibility during exercise, and post-exercise substrate metabolism will be measured pre-post intervention via indirect calorimetry. Secondary outcome of diet quality (kcal, carb, fat, protein) will be measured pre-post intervention via diet log. Exploratory outcomes of daily physical activity (steps, intensity), nightly sleep characteristics (quantity, quality, latency, efficiency), and daytime sleepiness and hunger.

Conditions

Overweight (BMI > 25); Obese But Otherwise Healthy Participants; Overweight or Obese; Obese Patients (BMI ≥ 30 kg/m²); Poor Sleep Quality; Healthy Participants; Physically Inactive

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Pistachio

Four days of pistachio snacking, to be consumed mid-morning (1oz; 9-11am), mid-afternoon (1oz; 2-4pm), and pre-sleep (0.5 oz; within 1hr of bedtime), while otherwise maintaining normal dietary habits. An addition snack will be consumed post-exercise (0.5oz).

Group Type: EXPERIMENTAL

Pistachio

Intervention Type: OTHER

Roasted, lightly salted, pistachio kernels (no shell)

Control

Maintain normal dietary habits for four days.

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

Pistachio

Roasted, lightly salted, pistachio kernels (no shell)

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Males and Females
• Age: 25-45 years
• Overweight or obese (BMI=25.0-34.9 kg/m²)
• Poor sleep quality (Pittsburgh Sleep Quality Index ≥ 5)
• Healthy (no diagnosed metabolic, cardiovascular, sleep, or other health condition that may significantly alter metabolism, sleep, or ability to participate in the exercise test)
• Not meeting weekly physical activity recommendations (<150 min moderate-intensity exercise, <75 minutes of vigorous-intensity exercise, and <2 days of strength training)
• Not following a diet that is restrictive or eliminates certain food group/types

Exclusion Criteria

• Allergies to nuts, especially tree nuts
• Has a pacemaker
• Following a diet that is restrictive or eliminates certain food group/types
• Self-repoted health or disease state that may influence study outcomes, including known metabolic or endocrine disorder (e.g. prediabetes, type 1 or type 2 diabetes, or polycystic ovary syndrome), cardiovascular diseases, neuromuscular disorders, musculoskeletal disorders; current or recent history of cancer/cancer treatment (within the past year)
• History of gastrointestinal surgery, hysterectomy
• For women: pregnant or thinking of becoming pregnant during the time of participation, pregnant within the last year, currently breastfeeding, or known to be perimenopausal

• Minimum Eligible Age: 25 Years
• Maximum Eligible Age: 45 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

American Pistachio Growers

OTHER

Sponsor Role: collaborator

University of South Carolina

OTHER

Sponsor Role: lead

Responsible Party

Katie Hirsch

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Katie R Hirsch, PhD

Role: PRINCIPAL_INVESTIGATOR

University of South Carolina

Locations

Public Health Research Center: Clinical Exercise Research Center

Columbia, South Carolina, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Callie Unrein, MS

Role: CONTACT

sustainlab@mailbox.sc.edu

803-777-5478

Other Identifiers

Pro00145186

Identifier Type: -

Identifier Source: org_study_id