Time-restricted Eating and Circadian Health in Night Shift Workers (FastingClocks)

Effect of a Time-restricted Eating Protocol on Glucose Homeostasis, Markers of Circadian System, Appetite Control, and Oxidative Stress Parameters in Night Shift Workers

The goal of this clinical trial is to learn about the effect of time-restricted eating (TRE) to 10 hours per day on glucose homeostasis, markers of the circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress status in night shift workers. The main questions it aims to answer are: 1) How does a time-restricted eating protocol affect glucose homeostasis in shift workers? and 2) How does a time-restricted eating protocol affect markers of the circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress status in shift workers? Participants will be asked to follow a TRE protocol on which they must restrict their eating to a self-selected time window of 10 hours a day, with mandatory fasting time between 24:00-06:00h. for 8 weeks. Researchers will compare the intervention with an additional period of 8 weeks, in which the participants will follow their usual diet without any time restriction, to see if the intervention improves glucose regulation appetite and markers of circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress.

Study Overview

• Status: Completed
• Conditions: Intermittent Fasting in Shift-work
• Intervention / Treatment: Behavioral: Time-restricted eating

Detailed Description

This is a randomized, crossover, controlled, within-subject study. After recruitment, participants will be randomized to one of two conditions: i) Time-restricted eating (TRE), with an eating window of 10 hours per day but without any other diet modification (e.g., types of food or amount of energy consumed). Each participant can freely choose the starting time of their eating window. If a participant need to make modifications to the start time of their eating window, he/she may do so only once during the TRE period, and the research team must be informed. After a washout period of at least 30 days, participants will undergo ii) Regular eating (REG), during which the participants must maintain their usual eating pattern (i.e., usual eating window), without making any dietary or lifestyle changes. Each condition will have a duration of 8 weeks. Randomization will be done using computer-generated random numbers.

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Chile
  • Metropolitan Region
    • Santiago, Metropolitan Region, Chile, 8380453
      • Faculty of Medicine, University of Chile

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Adults (range 18 - 60 yrs.) Men and women Performing as a healthcare worker Being a shift-worker for at least 6 months in the current schedule Working in rotating shiftwork, including at least one night shift Reporting no work-related performance difficulties

Exclusion Criteria:

• Current and chronic neurological disorders
• Pathologies related to abnormal adrenal activity
• Liver or kidney disease
• Uncontrolled hypertension, dyslipidemia, and thyroid disease
• Insulin resistance and T2D
• BMI ≥40 kg/m2
• Use of medications known to alter body composition, such as insulin sensitizers, glucocorticoids, or anti-depressants
• Autoimmune diseases with acute symptoms; recent surgery of any kind (in the last 3 months);
• Acute, chronic inflammation (usCRP >10 mg/L)
• Following any dietary restriction (special diet) in the previous three months
• Having a short sleep (habitual sleep duration of less than 6h per day)
• History of bariatric surgery
• Depression (Beck Depression Inventory) or sleep disorders (Pittsburgh Sleep Questionnaire)
• Night-eating syndrome (Night Eating Questionnaire)
• Intense exercise level (>3 days/week of high-intensity exercise)
• Having traveled across time zones (at any time during the last month) and planning travel during the study
• Pregnant or intend to become pregnant, and
• Lactating women

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Time-restricted eating; Self-selected eating window of 10 hours per day without any other dietary modification (e.g., types of food or amount of energy consumed) for 8 weeks, with 14 hours fasting per day (mandatory fasting from 00:00h until 06:00h).	Behavioral: Time-restricted eating; During the intervention (TRE) each participant will freely choose the starting time of their eating window. If needed, participant can modify the selected start time of their eating window only once during the intervention period, and the research team must be informed. After a washout period of at least 30 days, participants will undergo the opposite condition (TRE or Regular eating) after the initial randomization
No Intervention: Regular eating; Participants must maintain their usual eating pattern (i.e., usual eating window) for 8 weeks, but without any dietary or lifestyle changes

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in the mean fasting glycemia at 8 weeks	Fasting glycemia level (in mg/dL) will be measured from fasting blood samples and measured with the hexokinase method	From baseline to the end of treatment (at 8 weeks), in each study period (TRE and REG)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to end of treatment (8weeks) in 24-h glycemic control	24-h glycemic control (expressed in mg/dL), measured with continuous glucose monitoring (CGM) using a portable capillary glucose sensor, over 10 consecutive days.	From baseline to the end of treatment (at 8 weeks), in each study period (TRE and REG)
24-hour motor activity level (counts/min)	Motor activity will be assessed by accelerometric recordings (actigraphic data) of wrist activity. Actigraphy data will assess motor activity before and after the intervention	From enrollment to the end of treatment (at 8 weeks), in each study period (TRE and REG)
Change from Baseline in the circadian clock-genes expression at 8 weeks	Clock-gene expression will be evaluated by relative expression, performing RT-stem loop real-time PCR, from fasting whole-blood samples taken at baseline and after 8 weeks, in each study period. Gene expression levels of the target sequences will be normalized to the expression of GAPDH, and will be calculated by applying equation 2-∆∆ CT.	From baseline to the end of treatment (at 8 weeks), in each study period (TRE and REG)
Change from baseline in thiobarbituric acid reactive substances (TBARS) level at 8 weeks	TBARS level (in µM/ml) will be measured in plasma samples	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)]
Change from baseline in F-8 isoprostane level at 8 weeks	F-8 isoprostane level (in pg/mL) will be measured in plasma samples	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from Baseline in Appetite-related feelings at 8 weeks	A visual analog scale will be used to assess appetite feeling levels. Each participant rates their subjective feelings of appetite, satiety, and desire to eat using a 100 mm visual analog scale, with endpoints indicating from "not at all" (0 mm) to "extremely" (100 mm).	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in total-, reduced- and oxidized glutathione levels at 8 weeks	Total-, reduced-, and oxidized glutathione levels (in µM) will be measured in plasma samples	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in C-reactive protein levels at 8 weeks	C-reactive protein levels (in mg/L) will be measured in serum samples	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in pro-inflammatory cytokine levels at 8 weeks	Interleukin 1β, Interleukin 6, and Tumor necrosis factor (TNF-α) levels (in pg/mL) will be measured in plasma samples.	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in body mass index at 8 weeks	Body mass index will be calculated (expressed as kg/m2) from body weight and height anthropometric measurements, measured with light clothes and expressed as Kg (weight) and cm (height), respectively.	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in fat mass index at 8 weeks	Fat mass index (in kg/m²) will be assessed by dual-energy X-ray absorptiometry (DXA) using a Lunar DPXL densitometer	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from Baseline in sleep duration at 8 weeks	Sleep duration will be measured through continuous actigraphic recordings during daytime and nighttime for 10 days, and expressed in minutes	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in fat-free mass index at 8 weeks	Fat-free mass index (in kg/m²) will be assessed by dual-energy X-ray absorptiometry (DXA) using a Lunar DPXL densitometer	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in fat mass at 8 weeks	Fat mass (in %) will be assessed by dual-energy X-ray absorptiometry (DXA) using a Lunar DPXL densitometer	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in muscle mass at 8 weeks	Muscle mass (in %) will be estimated by dual-energy X-ray absorptiometry (DXA) using a Lunar DPXL densitometer	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)
Change from baseline in Bone Mineral Density at 8 weeks	Bone Mineral Density (BMD, in g/cm2) will be assessed by dual-energy X-ray absorptiometry (DXA) using a Lunar DPXL densitometer	From baseline to the end of treatment (8 weeks) in each study period (TRE and REG)

Collaborators and Investigators

• Sponsor: University of Chile
• Collaborators: Agencia Nacional de Investigación y Desarrollo
• Investigators: Study Chair: Lucía Cifuentes, MD, Ethics Committee for Human Subjects of the Faculty of Medicine, University of Chile

Study record dates

Study Major Dates

• Study Start (Actual): October 30, 2023
• Primary Completion (Actual): July 11, 2025
• Study Completion (Actual): July 11, 2025

Study Registration Dates

• First Submitted: January 30, 2026
• First Submitted That Met QC Criteria: February 27, 2026
• First Posted (Actual): March 5, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: intermittent fasting; healthcare; time-restricted eating; shiftwork
• Additional Relevant MeSH Terms: Behavior; Feeding Behavior; Fasting; Intermittent Fasting
• Other Study ID Numbers: TRE-Shift-2024

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Published data generated from the study will be available from the leading author, upon reasonable request

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No