Comparison of Time-Restricted Feeding Versus Grazing (TIMED EATING)

Time-Restricted Feeding to Improve Glucose Tolerance and Vascular Condition

The purpose of this pilot study is to find out what eating meals in a short time period early in the day (time-restricted feeding) versus eating meals spread out during the day (grazing) does to the body's ability to control blood sugar and to the health of its blood vessels.

The investigators hypothesize that time-restricted feeding will be more effective at improving glucose tolerance and vascular condition (inflammation and micro- and macro-vascular function) than grazing.

Study Overview

• Status: Completed
• Conditions: Vascular Diseases; Insulin Resistance; Prediabetes
• Intervention / Treatment: Other: Time-Restricted Feeding; Other: Grazing

Detailed Description

Each participant will eat according to one of the two eating schedules (grazing or time-restricted feeding) for 5 weeks, have a 7-week washout period, and then eat according to the other eating schedule for 5 weeks. Measurements of glucose homeostasis and vascular condition will be performed before and after a participant follows each eating schedule.

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Louisiana
    • Baton Rouge, Louisiana, United States, 70808
      • Pennington Biomedical Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 35 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Are male
• Overweight: Have a body mass index between 25 and 50 kg/m^2 inclusive (a number calculated from height and weight)
• Are 35-70 years of age
• Have a hemoglobin A1C between 5.5 - 6.4% or prior medical indication of prediabetes
• Have a blood sugar level between 140 and 199 mg/dL two hours after drinking a sugary solution (OGTT)
• Have been eating dinner at least 8.5 hours after eating breakfast at least 90% of the time during the past year
• Have not fasted (go for a day without any food) more than 12 days total during the past year
• Be willing to eat most meals at Pennington Biomedical and/or under supervision
• Not eat any food other than that served by Pennington Biomedical
• Not drink any alcohol, juice, or other beverages that have calories other than what is served by Pennington Biomedical
• Keep water and no-calorie drinks like tea or diet soda the same during both of the timed eating periods
• Be willing to eat your meals according to the fixed schedules

Exclusion Criteria:

• Have diabetes or are on anti-diabetes medication
• Have evidence of cardiovascular disease
• Suffer from significant cardiovascular, renal (kidney), cardiac (heart), liver, lung or nervous system disease
• Evidence of significant gastrointestinal issues or surgery that impacts nutrient absorption
• Regularly use medications such as steroids, beta blockers, and adrenergic-stimulating agents
• Are on any regular medicine that has not had the same dose for 1 month or longer
• Have a clinically significant abnormality as measured by a blood test
• Regularly drink alcohol (more than 2 servings per day)
• Have to do any kind of heavy physical activity
• Currently perform overnight shift work more than one day a week
• Are not able to eat only the food served to you by Pennington Biomedical, while in the study
• Are not able to stop drinking alcohol or other drinks with calories (e.g., soda, juice) other than what is served to you by Pennington Biomedical, while in the study

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Time-Restricted Feeding (early in the day eating); Participants will consume all meals early in the day and within a 6-hour window.	Other: Time-Restricted Feeding; Time-restricted feeding is a variant of intermittent fasting that involves eating all of one's calories within a few hours each day (typically 4-9 hours), followed by a daily fast of 15-20 hours.
Placebo Comparator: Grazing; Participants will eat meals spread out over the course of the day.	Other: Grazing; Grazing involves eating meals spread out over the course of the day.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Glucose Tolerance	Glucose tolerance and indices of glucose homeostasis will be determined using an Oral Glucose Tolerance Test (OGTT).	Before and after 5 weeks on each feeding schedule

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Vascular Function	Macro- and micro-vascular function will be assessed by Radial Artery Applanation Tonometry and by Orthogonal Polarization Spectroscopy. The endpoints measured by these two tests include aortic blood pressure, arterial stiffness, capillary density, and red blood cell velocity.	Before and after 5 weeks on each feeding schedule
Change in Inflammation and Metabolic Markers	Serum markers of inflammation, such as C-Reactive Protein (CRP) and inflammatory cytokines, and of metabolic processes will be measured (composite measure).	Before and after 5 weeks on each feeding schedule

Collaborators and Investigators

• Sponsor: Pennington Biomedical Research Center

Publications and helpful links

General Publications

• Allaf M, Elghazaly H, Mohamed OG, Fareen MFK, Zaman S, Salmasi AM, Tsilidis K, Dehghan A. Intermittent fasting for the prevention of cardiovascular disease. Cochrane Database Syst Rev. 2021 Jan 29;1:CD013496. doi: 10.1002/14651858.CD013496.pub2.

Study record dates

Study Major Dates

• Study Start: July 1, 2013
• Primary Completion (Actual): November 1, 2017
• Study Completion (Actual): November 1, 2017

Study Registration Dates

• First Submitted: July 3, 2013
• First Submitted That Met QC Criteria: July 9, 2013
• First Posted (Estimate): July 10, 2013

Study Record Updates

• Last Update Posted (Actual): March 16, 2018
• Last Update Submitted That Met QC Criteria: March 15, 2018
• Last Verified: March 1, 2018

More Information

Terms related to this study

• Keywords: Insulin resistance; Prediabetes; Insulin sensitivity; Glucose tolerance; Time-restricted feeding; Intermittent fasting; Circadian rhythms; Diurnal
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases; Diabetes Mellitus; Hyperinsulinism; Hyperglycemia; Vascular Diseases; Prediabetic State; Glucose Intolerance; Insulin Resistance
• Other Study ID Numbers: PBRC 13017

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