Obesity / OverweightNCT07853898
Effects of Pistachios on Postprandial Metabolic Responses in Adults With Overweight or Obesity
A study testing Pistachio Co-consumption in people with Obesity / Overweight, run by St. Louis University at 1 site in United States.
Trial summary
This randomized controlled crossover study will examine the acute effects of pistachio consumption on postprandial metabolic responses in adults with overweight or obesity. Participants will complete two experimental conditions in randomized order. Read more about this study
- Who is it for?
- Ages 18 to 35 years
- Conditions the study is for
- Obesity / Overweight
- What is being tested?
- Pistachio Co-consumption
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 28 participants
- Where
- 1 siteUnited States
- Study dates
- Oct 2026to Jul 2027
- 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 18 to 35 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Age 18-35 years, male or female, and able to provide informed consent.
- BMI ≥25.0 kg/m². Waist circumference and BIA-derived body composition will also be assessed during screening and considered with BMI to help confirm that elevated BMI reflects excess adiposity rather than primarily high muscularity.
- Weight stable, defined as no intentional weight loss or body weight change >3 kg during the previous 3 months.
- Generally healthy and not currently taking medications known to substantially affect glucose metabolism, insulin secretion, insulin sensitivity, appetite, or body weight. Stable thyroid hormone replacement for a well-controlled thyroid condition is not automatically exclusionary.
- Able to complete a 10-12-hour overnight fast and refrain from vigorous exercise and alcohol for 24 hours before each test meal visit.
- Able and willing to consume pistachios, the refined-carbohydrate control food, and the standardized breakfast meal.
Who cannot join
- Known diagnosis of type 1 or type 2 diabetes. Individuals with known prediabetes will not be excluded.
- Clinically significant cardiovascular disease, including prior myocardial infarction or stroke, uncontrolled hypertension, clinically significant arrhythmia, or another cardiovascular condition that could make participation unsafe or meaningfully affect study outcomes.
- Chronic kidney disease or another major medical condition that could make participation unsafe or meaningfully affect metabolic outcomes.
- Current participation in a weight-loss program, use of weight-loss medications, or history of bariatric surgery within the past year.
- Known allergy or intolerance to pistachios, tree nuts, peanuts/peanut butter, wheat/gluten, orange juice/citrus, or any other study-meal ingredient.
- Celiac disease, Crohn's disease, ulcerative colitis, or another clinically significant gastrointestinal or malabsorption condition that could affect digestion, nutrient absorption, or metabolic responses.
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- Current ketogenic, very-low-carbohydrate, or medically prescribed diet that could meaningfully interfere with the standardized feeding protocol or metabolic outcomes.
- Participation in another clinical research trial within the past 3 months that could affect participant safety or study outcomes.
- Recent significant illness, infection, or surgery within the past 4 weeks that could affect participant safety or study outcomes.
- Current or prior clinically significant eating disorder that, in the investigator's judgment, could make participation unsafe or interfere with the feeding protocol.
- Current smoking, frequent nicotine use, or excessive alcohol use.
- Pregnancy, planned pregnancy during the study period, or lactation.
- Any condition or medication that, in the investigator's judgment, would make participation unsafe or interfere with outcome measures.
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
Saint Louis University
St Louis, Missouri, 63104
Hossein Rafiei, PhD RD, 314-977-8675, hossein.rafiei@health.slu.edu
Hossein Rafiei, PhD, RD
About this study
Official title: Acute Effects of Pistachio Consumption on Postprandial Metabolic Responses in Adults With Overweight or Obesity: A Randomized Controlled Crossover Trial
This randomized controlled crossover study will examine the acute effects of pistachio consumption on postprandial metabolic responses in adults with overweight or obesity. Participants will complete two experimental conditions in randomized order. In one condition, participants will consume 30 g of pistachios with a standardized meal, and in the other condition they will receive an isocaloric refined-carbohydrate control condition with the standardized meal.
The study will evaluate postprandial insulin and glucose responses over approximately 3 hours after meal consumption. Additional outcomes will include continuous glucose monitoring measures, blood lipid responses, appetite and satiety ratings, and exploratory measures related to insulin sensitivity and gastrointestinal hormone responses. The study is designed to determine whether pistachio consumption alters acute metabolic responses compared with an isocaloric refined-carbohydrate control in adults with overweight or obesity.
Read the detailed description
This study is a randomized, controlled, crossover feeding trial designed to investigate the acute effects of pistachio consumption on postprandial metabolic responses in adults with overweight or obesity. Each participant will complete both experimental conditions in randomized order, thereby serving as their own control. Experimental visits will be separated by a washout period.
After an overnight fast, participants will receive either 30 g of pistachios or an isocaloric refined-carbohydrate control with a standardized meal. Serial blood samples will be collected during the postprandial period to assess insulin and glucose responses. The primary metabolic outcome will focus on the postprandial insulin response over the 0- to 180-minute period.
Additional outcomes will characterize postprandial glucose responses, including measures obtained using continuous glucose monitoring, as well as appetite and satiety ratings and blood lipid responses. Exploratory analyses may include indices of insulin sensitivity and resistance and gastrointestinal hormones involved in metabolic regulation. The crossover design will allow direct within-participant comparison of the pistachio and control conditions.
- Conditions
- Obesity / Overweight
- Being tested
- Pistachio Co-consumption, Refined-Carbohydrate Control Co-consumption
- Keywords
- Pistachios, Postprandial glucose, Postprandial insulin, Metabolic response, Insulin sensitivity, Continuous glucose monitoring, Appetite
- Medical subject headings
- Obesity, Overweight, Insulin Resistance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pistachio Co-consumptionOther
Participants will consume 30 g of shelled, lightly salted pistachios together with a standardized high-glycemic breakfast meal. The pistachios and standardized breakfast meal will be consumed within a fixed 10-minute meal period.
Refined-Carbohydrate Control Co-consumptionOther
Participants will consume an isocaloric refined-carbohydrate control food together with the same standardized high-glycemic breakfast meal. The control food will be matched to the pistachio condition for energy content as closely as possible while providing minimal fiber, protein, unsaturated fat, and bioactive compounds.
| Study group | Role | What they receive |
|---|---|---|
| Pistachio Then Control Sequence | Experimental | Participants randomized to this sequence will first complete the pistachio condition, in which 30 g of shelled pistachios are consumed with the standardized high-glycemic breakfast meal. After a 3-7 day washout period, participants will complete the refined-carbohydrate control condition, in which an isocaloric refined-carbohydrate control food is consumed with the same standardized breakfast meal. Receives: Other: Pistachio Co-consumption; Other: Refined-Carbohydrate Control Co-consumption |
| Control Then Pistachio Sequence | Experimental | Participants randomized to this sequence will first complete the refined-carbohydrate control condition, in which an isocaloric refined-carbohydrate control food is consumed with the standardized high-glycemic breakfast meal. After a 3-7 day washout period, participants will complete the pistachio condition, in which 30 g of shelled pistachios are consumed with the same standardized breakfast meal. Receives: Other: Pistachio Co-consumption; Other: Refined-Carbohydrate Control Co-consumption |
What is being measured
The primary outcome is the main question the study is designed to answer.
Postprandial Insulin Incremental Area Under the Curve (iAUC)
Postprandial plasma insulin will be measured at 0, 30, 60, 90, 120, 150, and 180 minutes after meal consumption. Insulin incremental area under the curve (iAUC) from 0 to 180 minutes will be calculated using the trapezoidal rule with baseline subtraction. Insulin iAUC will be compared between the pistachio and refined-carbohydrate control conditions.
Measured: 0-180 minutes after meal consumption
Secondary outcomes (10)
Postprandial Plasma Glucose Incremental Area Under the Curve (iAUC)
Plasma glucose concentrations will be measured at 0, 30, 60, 90, 120, 150, and 180 minutes after meal consumption. Glucose iAUC from 0 to 180 minutes will be calculated using the trapezoidal rule with baseline subtraction and compared between conditions.
Measured: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Time in Range
Percentage of CGM glucose readings within the predefined range of 70-180 mg/dL during the postprandial laboratory monitoring period will be calculated and compared between the pistachio and refined-carbohydrate control conditions.
Measured: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Mean Glucose
Mean interstitial glucose concentration measured by continuous glucose monitoring during the postprandial laboratory monitoring period will be calculated and compared between conditions.
Measured: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Glycemic Variability
Glycemic variability will be assessed using the coefficient of variation (CV) of CGM-derived interstitial glucose concentrations during the postprandial monitoring period and compared between conditions.
Measured: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Peak Glucose
The highest interstitial glucose concentration recorded by continuous glucose monitoring during the postprandial monitoring period will be determined and compared between conditions.
Measured: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Time to Peak Glucose
Time from meal consumption to the highest CGM-derived interstitial glucose concentration during the postprandial monitoring period will be determined and compared between conditions.
Measured: 0-180 minutes after meal consumption
Postprandial Hunger Rating
Self-reported hunger will be assessed using a 100-mm visual analog scale (VAS) at baseline and 30, 60, 120, and 180 minutes after meal consumption and compared between conditions.
Measured: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Fullness Rating
Self-reported fullness will be assessed using a 100-mm visual analog scale (VAS) at baseline and 30, 60, 120, and 180 minutes after meal consumption and compared between conditions.
Measured: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Satisfaction Rating
Self-reported satisfaction will be assessed using a 100-mm visual analog scale (VAS) at baseline and 30, 60, 120, and 180 minutes after meal consumption and compared between conditions.
Measured: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Desire to Eat Rating
Self-reported desire to eat will be assessed using a 100-mm visual analog scale (VAS) at baseline and 30, 60, 120, and 180 minutes after meal consumption and compared between conditions.
Measured: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Oct 2026
- Study startOct 2026 (estimated)
- Primary completionJul 2027 (estimated)
- Study completionJul 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity / OverweightStudies 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 28 participants (estimated)
Sponsor and investigators
- Lead sponsor
- St. Louis University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Hossein Rafiei, St. Louis University
- Investigators
- Hossein Rafiei, PhD, RD, Principal investigator, St. Louis University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07853898
- Sponsor's protocol ID
- STUDY00000569
- Status last verified
- Sep 2026
- First submitted
- 26 Sep 2026
- Last updated
- 2 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data are not currently planned to be shared with researchers outside the study team. Study results will be reported in aggregate or de-identified form in accordance with applicable institutional, ethical, and privacy requirements.
Study at a glance
From the registry record, last updated by the sponsor on 2 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Acute Effects of Pistachio Consumption on Postprandial Metabolic Responses in Adults With Overweight or Obesity: A Randomized Controlled Crossover Trial
- ClinicalTrials.gov ID
- NCT07853898
- Acronym / sponsor ID
- STUDY00000569
- Conditions
- Obesity / Overweight
- Keywords
- Pistachios, Postprandial glucose, Postprandial insulin, Metabolic response, Insulin sensitivity, Continuous glucose monitoring, Appetite
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 28 participants (estimated)
- Lead sponsor
- St. Louis UniversityUniversity, hospital or other
- Study start
- Oct 2026 (estimated)
- Primary completion
- Jul 2027 (estimated)
- Study completion
- Jul 2027 (estimated)
- First posted
- 2 Oct 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.
This randomized controlled crossover study will examine the acute effects of pistachio consumption on postprandial metabolic responses in adults with overweight or obesity. Participants will complete two experimental conditions in randomized order. In one condition, participants will consume 30 g of pistachios with a standardized meal, and in the other condition they will receive an isocaloric refined-carbohydrate control condition with the standardized meal.
The study will evaluate postprandial insulin and glucose responses over approximately 3 hours after meal consumption. Additional outcomes will include continuous glucose monitoring measures, blood lipid responses, appetite and satiety ratings, and exploratory measures related to insulin sensitivity and gastrointestinal hormone responses. The study is designed to determine whether pistachio consumption alters acute metabolic responses compared with an isocaloric refined-carbohydrate control in adults with overweight or obesity.
Detailed description
This study is a randomized, controlled, crossover feeding trial designed to investigate the acute effects of pistachio consumption on postprandial metabolic responses in adults with overweight or obesity. Each participant will complete both experimental conditions in randomized order, thereby serving as their own control. Experimental visits will be separated by a washout period.
After an overnight fast, participants will receive either 30 g of pistachios or an isocaloric refined-carbohydrate control with a standardized meal. Serial blood samples will be collected during the postprandial period to assess insulin and glucose responses. The primary metabolic outcome will focus on the postprandial insulin response over the 0- to 180-minute period.
Additional outcomes will characterize postprandial glucose responses, including measures obtained using continuous glucose monitoring, as well as appetite and satiety ratings and blood lipid responses. Exploratory analyses may include indices of insulin sensitivity and resistance and gastrointestinal hormones involved in metabolic regulation. The crossover design will allow direct within-participant comparison of the pistachio and control conditions.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Pistachio Then Control Sequence | Experimental | Other: Pistachio Co-consumption, Other: Refined-Carbohydrate Control Co-consumptionParticipants randomized to this sequence will first complete the pistachio condition, in which 30 g of shelled pistachios are consumed with the standardized high-glycemic breakfast meal. After a 3-7 day washout period, participants will complete the refined-carbohydrate control condition, in which an isocaloric refined-carbohydrate control food is consumed with the same standardized breakfast meal. |
| Control Then Pistachio Sequence | Experimental | Other: Pistachio Co-consumption, Other: Refined-Carbohydrate Control Co-consumptionParticipants randomized to this sequence will first complete the refined-carbohydrate control condition, in which an isocaloric refined-carbohydrate control food is consumed with the standardized high-glycemic breakfast meal. After a 3-7 day washout period, participants will complete the pistachio condition, in which 30 g of shelled pistachios are consumed with the same standardized breakfast meal. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Age 18-35 years, male or female, and able to provide informed consent.
- BMI ≥25.0 kg/m². Waist circumference and BIA-derived body composition will also be assessed during screening and considered with BMI to help confirm that elevated BMI reflects excess adiposity rather than primarily high muscularity.
- Weight stable, defined as no intentional weight loss or body weight change >3 kg during the previous 3 months.
- Generally healthy and not currently taking medications known to substantially affect glucose metabolism, insulin secretion, insulin sensitivity, appetite, or body weight. Stable thyroid hormone replacement for a well-controlled thyroid condition is not automatically exclusionary.
- Able to complete a 10-12-hour overnight fast and refrain from vigorous exercise and alcohol for 24 hours before each test meal visit.
Key exclusion criteria (13 listed)
- Known diagnosis of type 1 or type 2 diabetes. Individuals with known prediabetes will not be excluded.
- Clinically significant cardiovascular disease, including prior myocardial infarction or stroke, uncontrolled hypertension, clinically significant arrhythmia, or another cardiovascular condition that could make participation unsafe or meaningfully affect study outcomes.
- Chronic kidney disease or another major medical condition that could make participation unsafe or meaningfully affect metabolic outcomes.
- Current participation in a weight-loss program, use of weight-loss medications, or history of bariatric surgery within the past year.
- Known allergy or intolerance to pistachios, tree nuts, peanuts/peanut butter, wheat/gluten, orange juice/citrus, or any other study-meal ingredient.
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 |
|---|---|---|
| Pistachio Co-consumptionParticipants will consume 30 g of shelled, lightly salted pistachios together with a standardized high-glycemic breakfast meal. The pistachios and standardized breakfast meal will be consumed within a fixed 10-minute meal period. | Other | Control Then Pistachio Sequence, Pistachio Then Control Sequence |
| Refined-Carbohydrate Control Co-consumptionParticipants will consume an isocaloric refined-carbohydrate control food together with the same standardized high-glycemic breakfast meal. The control food will be matched to the pistachio condition for energy content as closely as possible while providing minimal fiber, protein, unsaturated fat, and bioactive compounds. | Other | Control Then Pistachio Sequence, Pistachio Then Control Sequence |
Primary outcome
Postprandial Insulin Incremental Area Under the Curve (iAUC)
Time frame: 0-180 minutes after meal consumption
Postprandial plasma insulin will be measured at 0, 30, 60, 90, 120, 150, and 180 minutes after meal consumption. Insulin incremental area under the curve (iAUC) from 0 to 180 minutes will be calculated using the trapezoidal rule with baseline subtraction. Insulin iAUC will be compared between the pistachio and refined-carbohydrate control conditions.
10 secondary outcomes
Postprandial Plasma Glucose Incremental Area Under the Curve (iAUC)
Time frame: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Time in Range
Time frame: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Mean Glucose
Time frame: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Glycemic Variability
Time frame: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Peak Glucose
Time frame: 0-180 minutes after meal consumption
Continuous Glucose Monitoring Time to Peak Glucose
Time frame: 0-180 minutes after meal consumption
Postprandial Hunger Rating
Time frame: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Fullness Rating
Time frame: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Satisfaction Rating
Time frame: Baseline and 30, 60, 120, and 180 minutes after meal consumption
Postprandial Desire to Eat Rating
Time frame: Baseline and 30, 60, 120, and 180 minutes after meal consumption
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 2 Oct 2026.
- Individual participant dataSharing planned: No. Individual participant data are not currently planned to be shared with researchers outside the study team. Study results will be reported in aggregate or de-identified form in accordance with applicable institutional, ethical, and privacy requirements.
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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.
Hossein Rafiei, PhD, RD principal investigator
St. Louis University
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 Co-consumption in people with Obesity / Overweight, run by St. Louis University 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 6 inclusion and 13 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 2 Oct 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 Hossein Rafiei, PhD, RD (314-977-8675, hossein.rafiei@health.slu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Postprandial Insulin Incremental Area Under the Curve (iAUC) (time frame: 0-180 minutes after meal consumption). 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 2 Oct 2026.