Overweight (BMI > 25)NCT07340125
Pistachio Snacking and Metabolic Flexibility
A study testing Pistachio in people with Overweight (BMI > 25) and Obese But Otherwise Healthy Participants, run by University of South Carolina at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 25 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Overweight (BMI > 25), Obese But Otherwise Healthy Participants, Overweight or Obese
- What is being tested?
- Pistachio
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Sep 2025to 31 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 25 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Public Health Research Center: Clinical Exercise Research Center
Columbia, South Carolina, 29208
About this study
Official title: Effects of Pistachio Snacking on Metabolic Flexibility in Healthy Overweight and Obese Adults
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
- Being tested
- Pistachio
- Keywords
- Pistachio, Tree Nuts, metabolic flexibility, metabolism, diet quality, snacking
- Medical subject headings
- Overweight, Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PistachioOther
Roasted, lightly salted, pistachio kernels (no shell)
| Study group | Role | What they receive |
|---|---|---|
| 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). Receives: Other: Pistachio |
| Control | No intervention | Maintain normal dietary habits for four days. |
What is being measured
The primary outcome is the main question the study is designed to answer.
resting metabolism
resting metabolic rate (RMR) and substrate utilization (RER) via indirect calorimetry
Measured: Day 0 and Day 5
exercise metabolic flexibility
substrate metabolism (RER; indirect calorimetry) throughout a submaximal, graded exercise test
Measured: 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
Measured: Day 0 and Day 5
Secondary outcomes (4)
Caloric Intake
Average calorie intake (kcal) via 24-hr diet record
Measured: Day 0 and Day 4
Carbohydrate Intake
Average carbohydrate intake (grams) via 24-hr diet record
Measured: Day 0 and Day 4
Protein Intake
Average protein intake (grams) via 24-hr diet record
Measured: Day 0 and Day 4
Fat Intake
Average fat intake (grams) via 24-hr diet record
Measured: Day 0 and Day 4
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jan 2026
- Study start1 Sep 2025
- Primary completion1 Aug 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Overweight (BMI > 25)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Randomized, crossover
- Masking
- None (open label)
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of South Carolina
- Sponsor type
- University, hospital or other
- Collaborators
- American Pistachio Growers
- Responsible party
- Principal investigator, Katie Hirsch, University of South Carolina
- Investigators
- Katie R Hirsch, PhD, Principal investigator, University of South Carolina
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07340125
- Sponsor's protocol ID
- Pro00145186
- Status last verified
- Jan 2026
- First submitted
- 17 Dec 2025
- Last updated
- 14 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: data may be shared upon reasonable request.
Study at a glance
From the registry record, last updated by the sponsor on 14 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Pistachio Snacking on Metabolic Flexibility in Healthy Overweight and Obese Adults
- ClinicalTrials.gov ID
- NCT07340125
- Acronym / sponsor ID
- Pro00145186
- Conditions
- Overweight (BMI > 25), Obese But Otherwise Healthy Participants, Overweight or Obese, Obese Patients (BMI ≥ 30 kg/m²), Poor Sleep Quality, Healthy Participants
- Keywords
- Pistachio, Tree Nuts, metabolic flexibility, metabolism, diet quality, snacking
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- University of South CarolinaUniversity, hospital or other
- Collaborators
- American Pistachio Growers
- Study start
- 1 Sep 2025 (actual)
- Primary completion
- 1 Aug 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 14 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Randomized, crossover
| Arm | Type | Receives |
|---|---|---|
| Pistachio | Experimental | Other: PistachioFour 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). |
| Control | No intervention | –Maintain normal dietary habits for four days. |
Who may qualify
- Ages
- 25 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- 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)
Key exclusion criteria (6 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| PistachioRoasted, lightly salted, pistachio kernels (no shell) | Other | Pistachio |
Primary outcome
resting metabolism
Time frame: Day 0 and Day 5
resting metabolic rate (RMR) and substrate utilization (RER) via indirect calorimetry
exercise metabolic flexibility
Time frame: Day 0 and Day 5
substrate metabolism (RER; indirect calorimetry) throughout a submaximal, graded exercise test
post-exercise metabolism
Time frame: Day 0 and Day 5
Energy expenditure and substrate metabolism (RER) measured at 0, 30, 60, 90min post-exercise via indirect calorimetry
4 secondary outcomes
Caloric Intake
Time frame: Day 0 and Day 4
Carbohydrate Intake
Time frame: Day 0 and Day 4
Protein Intake
Time frame: Day 0 and Day 4
Fat Intake
Time frame: Day 0 and Day 4
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Jan 2026.
- Individual participant dataSharing planned: No. data may be shared upon reasonable request.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Katie R Hirsch, PhD principal investigator
University of South Carolina
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Pistachio in people with Overweight (BMI > 25) and Obese But Otherwise Healthy Participants, run by University of South Carolina at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 14 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Callie Unrein, MS (803-777-5478, sustainlab@mailbox.sc.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
resting metabolism (time frame: Day 0 and Day 5). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Jan 2026.