The Metabolic Effects of Intermittent Fasting

The Effects of Fasting on Reprogramming of Lipid Metabolism and Bone Metabolism

Caloric restriction has beneficial metabolic effects in humans including weight loss and improvement in blood pressure and lipid levels. Intermittent fasting has emerged as a popular alternative to caloric restriction as it does not require daily adherence to a dietary protocol, but whether the benefits of fasting protocols are dependent on weight loss is not known. In this study, the investigators will explore the metabolic effects of fasting and evaluate whether these effects, including negative effects on bone metabolism, are independent of weight loss.

Study Overview

• Status: Recruiting
• Conditions: Normal and Overweight Individuals at High-risk of Diabetes
• Intervention / Treatment: Behavioral: Fasting arm; Behavioral: Weight maintenance; Behavioral: Counseling

• Study Type: Interventional
• Enrollment (Estimated): 90
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Pouneh Fazeli, MD; Phone Number: 412-648-9770; Email: pkfazeli@pitt.edu

Study Locations

• United States
  • Pennsylvania
    • Pittsburgh, Pennsylvania, United States, 15213
      • Recruiting
      • University of Pittsburgh
      • Contact: Pouneh Fazeli, MD; Email: pkfazeli@pitt.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years to 45 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Men and women, ages 21-45 years
2. BMI of at least 21 kg/m2 and up to and including BMI of 29 kg/m2
3. Normal thyroid function
4. Regular menses (women)
5. At least one first-degree relative with type 2 diabetes (T2D) and/or history of gestational diabetes

Exclusion Criteria:

1. Any chronic diseases including hypertension and Type 2 diabetes mellitus
2. Indication for lipid-lowering therapy in non-diabetics, using the more stringent AHA guideline cutoff (LDL>190 or an estimated 10-year ASCVD risk of >7.5%)
3. Chronic medications, including oral contraceptive pills
4. Pregnant and/or breastfeeding
5. History of an eating disorder
6. 25-OH vitamin D level < 20 ng/mL
7. Active substance abuse, including alcohol
8. Subjects with a prior history of intermittent fasting
9. The study physician feels that the subject may not be able to safely complete the protocol or may place themselves at risk by undergoing the protocol

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Fasting; Subjects will fast one-day per week for 12 weeks	Behavioral: Fasting arm; Study participants will fast one day per week for 12 weeks
Experimental: Fasting with weight maintenance; Subjects will fast one-day per week for 12 weeks and maintain body weight	Behavioral: Fasting arm; Study participants will fast one day per week for 12 weeks; Behavioral: Weight maintenance; Study participants will be counseled to maintain body weight
Placebo Comparator: Counseling; Subjects will be counseled on optimal diet and activity recommendations to maintain/achieve a normal BMI (standard of care)	Behavioral: Counseling; Study participants will be counseled on optimal diet and activity recommendations for maintaining/achieving a normal BMI

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Triglyceride carbon content and degree of saturation	Change in triglyceride carbon content and degree of saturation (% variation explained by both carbon number and double bond number in a regression model) between Baseline and Final Intervention visits	Baseline, 3 months
Trabecular bone microarchitecture	Change in trabecular bone volume fraction at the radius between Baseline and Final Intervention visits	Baseline, 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Insulin sensitivity	Change in insulin sensitivity as assessed by hyperinsulinemic-euglycemic clamp between Baseline and Final Intervention visits	Baseline, 3 months

Collaborators and Investigators

• Sponsor: University of Pittsburgh
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Investigators: Principal Investigator: Pouneh Fazeli, MD, University of Pittsburgh

Publications and helpful links

General Publications

• Quaytman JA, David NL, Venugopal S, Amorim T, Beatrice B, Toledo FGS, Miller RG, Steinhauser ML, Fazeli PK. Intermittent fasting for systemic triglyceride metabolic reprogramming (IFAST): Design and methods of a prospective, randomized, controlled trial. Contemp Clin Trials. 2024 Nov;146:107698. doi: 10.1016/j.cct.2024.107698. Epub 2024 Sep 17.

Study record dates

Study Major Dates

• Study Start (Actual): October 25, 2023
• Primary Completion (Estimated): June 30, 2028
• Study Completion (Estimated): June 30, 2028

Study Registration Dates

• First Submitted: January 27, 2023
• First Submitted That Met QC Criteria: February 1, 2023
• First Posted (Actual): February 10, 2023

Study Record Updates

• Last Update Posted (Actual): May 18, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Physiological Phenomena; Health Services; Health Care Facilities Workforce and Services; Community Health Services; Behavioral Disciplines and Activities; Mental Health Services; Body Size; Growth; Growth and Development; Body Weight; Counseling; Body Weight Maintenance
• Other Study ID Numbers: STUDY21120112; R01DK133578 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Deidentified information will be shared upon request.
• IPD Sharing Time Frame: Beginning 12 months after publication. No end date.
• IPD Sharing Access Criteria: Researchers who wish to access deidentified data.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No