Low-calorie Diet in Isolated Impaired Fasting Glucose

June 15, 2026 updated by: Mary Beth Weber, Emory University

Effect of Dietary Energy Restriction on Reversing Isolated Impaired Fasting Glucose: A Proof of Concept Study

This study aims to evaluate the preliminary efficacy of a low-calorie diet (LCD) intervention in addressing the underlying pathophysiological abnormalities and improving fasting hyperglycemia among individuals with isolated impaired fasting glucose (i-IFG). Additionally, it seeks to assess the feasibility and acceptability of the LCD intervention.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Withdrawn

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This proof-of-concept randomized controlled trial (RCT) will enroll 34 individuals aged 35-65 years with overweight or obesity and isolated impaired fasting glucose. Intervention participants will adhere to an 8-week low-calorie dietary (LCD) regimen (~1,320 kcal/day) comprising specific macronutrient proportions (55% carbohydrate, 13% fat, 25% protein, and 2% fiber). Control participants will maintain their habitual dietary habits and physical activity levels. Primary outcomes at 8 weeks include between-group changes in weight, fasting plasma glucose, indices of ß-cell function and hepatic insulin resistance, and alanine aminotransferase levels. Secondary outcomes are feasibility metrics (response rate, screening yield, enrollment rate, intervention compliance, cost, staff time, and retention rate) and intervention acceptability. Qualitative research will explore facilitators, barriers, acceptability, satisfaction, and participant experiences with the LCD intervention.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Georgia Clinical & Translational Science Alliance (CTSA) Clinical Research Centers (GCRCs)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. Aged 35 to 65 years
  2. Overweight (body mass index (BMI) ≥25 to <29 kg/m² or ≥23 to <29 kg/m² if Asian descent) or Obese (BMI ≥30 kg/m²)
  3. Physically inactive (<150 minutes per week of moderate-intensity physical activity or <75 minutes per week of vigorous-intensity physical activity)
  4. Prediabetes diagnosis or score ≥5 on the American Diabetes Association (ADA) risk tool

Exclusion Criteria:

  1. Diagnosed with type 1 or type 2 diabetes
  2. Cardiovascular disease (myocardial infarction, stroke, angina, heart failure, or other cardiac conditions)
  3. Chronic kidney disease
  4. Chronic liver disease (e.g., cirrhosis)
  5. Cancers
  6. Acute inflammatory bowel disease, irritable bowel syndrome, celiac disease, chronic pancreatitis, or other disorders potentially causing malabsorption
  7. Food allergies
  8. Participation in weight loss programs in the past six months
  9. Currently following a specific diet (e.g., ketogenic diet, Mediterranean diet)
  10. Participation in any exercise programs in the past six months
  11. Currently taking weight-loss medications or drugs known to affect glycemia (steroids and antipsychotics)
  12. Previous bariatric surgery or plan to have bariatric surgery during the study period
  13. Planning to relocate during the study period
  14. Intending to fast during the study period for religious or other reasons
  15. Pregnancy or planning to become pregnant during the study period
  16. Breastfeeding
  17. Non-English speaker

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Low-calorie diet
Participants following a low-calorie diet (LCD) consisting of approximately 1,300 kcal/day (37% carbohydrates, 25% protein, 39% fat, and 7 g of fiber per meal) over an eight-week period.
Behavioral: Low-calorie diet
The low-calorie diet consists of approximately 1,300 kcal/day (37% carbohydrates, 25% protein, 39% fat, and 7 g of fiber per meal) over an eight-week period. Participants receive weekly pre-prepared meals from Trifecta Nutrition (Trifecta Inc. California, USA) with options for breakfast, lunch, and dinner, meticulously crafted by certified dieticians and expert chefs. Participants are encouraged to consume 1-2 liters of water daily and maintain their habitual physical activity levels.
Other Names:
  • Dietary energy restriction
Active Comparator: Routine dietary and physical activity habits
Control participants are asked to maintain their routine dietary and physical activity habits.
Behavioral: Routine dietary and physical activity habits
Participants are asked to maintain their habitual dietary and physical activity habits for the 8-week study period.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Response rate
Time Frame: Baseline
Response rate is defined as the proportion of individuals responding to the invitation sent via the Epic database.
Baseline
Screening yield
Time Frame: Baseline
Screening yield: Proportion of screened individuals meeting eligibility criteria.
Baseline
Enrollment rate
Time Frame: Baseline
Enrollment rate: Proportion of eligible individuals who enroll in the study.
Baseline
Resource utilization
Time Frame: Throughout the study period, an average of 10 weeks
Resource utilization: Assessment of expenditures and staff time.
Throughout the study period, an average of 10 weeks
Retention rate
Time Frame: 4 and 8 weeks
Retention rate: Proportion of enrolled participants who complete the study.
4 and 8 weeks
Intervention acceptability
Time Frame: 4 and 8 weeks
Intervention acceptability will be assessed using the Theoretical Framework of Acceptability questionnaire. Scores range from 7 to 35. Higher scores indicate better acceptability among participants.
4 and 8 weeks
Feasibility of intervention
Time Frame: 4 and 8 weeks
Will be assessed using the Feasibility of Intervention Measure questionnaire. Scores range from 4 to 20. Higher scores indicate better feasibility among participants.
4 and 8 weeks
Intervention appropriateness
Time Frame: 4 and 8 weeks
Will be assessed with the Intervention Appropriateness Measure questionnaire. Scores range from 4 to 20. Higher scores indicate better appropriateness among participants.
4 and 8 weeks
Facilitators, barriers, acceptability, satisfaction, and participant experiences with the the intervention
Time Frame: 4 and 8 weeks
Qualitative in-depth interviews
4 and 8 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Fasting plasma glucose in mg/dl
Time Frame: 4 and 8 weeks
Will be analyzed by enzymatic assays
4 and 8 weeks
Alanine aminotransferase (liver enzyme) in U/L
Time Frame: 4 and 8 weeks
Will be analyzed with colorimetric assays
4 and 8 weeks
Weight in kg
Time Frame: 4 and 8 weeks
Weight will be measured using a digital weighing scale with an accuracy to the nearest 0.1 kg
4 and 8 weeks
Indices of ß-cell function
Time Frame: 4 and 8 weeks
Will be assessed using the insulinogenic index (IGI)
4 and 8 weeks
ß-cell function assessed by Oral Disposition Index (DI(O))
Time Frame: 4 and 8 weeks
Will be assessed using the Oral Disposition Index (DI(O))
4 and 8 weeks
ß-cell function assessed by Homeostatic Model Assessment of ß-cell Function (HOMA-B)
Time Frame: 4 and 8 weeks
Will be assessed using the Homeostatic Model Assessment of ß-cell Function (HOMA-B)
4 and 8 weeks
Indices of hepatic insulin resistance
Time Frame: 4 and 8 weeks
Will be assessed using the Hepatic Insulin Resistance Index (HIRI)
4 and 8 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Emory University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Sathish Thirunavukkarasu, PhD, Emory University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 30, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 30, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 31, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 8, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 10, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 15, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • STUDY00007848
  • 2025P012671 (Other Identifier: Emory IRB)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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