Pistachio Snacking and Metabolic Flexibility

NCT07340125 | Recruiting

• 1 other identifier: Pro00145186
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

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

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

Keywords

Pistachio; Tree Nuts; metabolic flexibility; metabolism; diet quality; snacking

Outcome Measures

Primary Outcomes (3)

• resting metabolism

  resting metabolic rate (RMR) and substrate utilization (RER) via indirect calorimetry

  Day 0 and Day 5

• exercise metabolic flexibility

  substrate metabolism (RER; indirect calorimetry) throughout a submaximal, graded exercise test

  Day 0 and Day 5

• post-exercise metabolism

  Energy expenditure and substrate metabolism (RER) measured at 0, 30, 60, 90min post-exercise via indirect calorimetry

  Day 0 and Day 5

Secondary Outcomes (4)

• Caloric Intake

  Day 0 and Day 4

• Carbohydrate Intake

  Day 0 and Day 4

• Protein Intake

  Day 0 and Day 4

• Fat Intake

  Day 0 and Day 4

Other Outcomes (5)

• Physical Activity

  daily continuous (Day 0 to Day 5)

• Sleep Quantity

  Nightly (Day 0 to Day 5)

• Sleep Quality

  Nightly (Day 0 to Day 5)

Study Arms (2)

Pistachio

EXPERIMENTAL

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).

Other: Pistachio

Control

NO INTERVENTION

Maintain normal dietary habits for four days.

Interventions

Pistachio OTHER

Roasted, lightly salted, pistachio kernels (no shell)

Pistachio

Eligibility Criteria

• Age: 25 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• University of South Carolina: lead
• American Pistachio Growers: collaborator

Study Sites (1)

Public Health Research Center: Clinical Exercise Research Center

Columbia, South Carolina, 29208, United States

RECRUITING

MeSH Terms

Conditions

Overweight; Obesity

Condition Hierarchy (Ancestors)

Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Katie R Hirsch, PhD

  University of South Carolina

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Callie Unrein, MS

CONTACT

803-777-5478; sustainlab@mailbox.sc.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Model Details: Randomized, crossover

Study Record Dates

• First Submitted: December 17, 2025
• First Posted: January 14, 2026
• Study Start: September 1, 2025
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): December 31, 2026
• Last Updated: January 14, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)