The Feasibility of Overnight Time Restricted Eating and Impact on Glucose Levels in Shift Workers (TREsh)

The Effect of Overnight Time Restricted Eating on Glucose Regulation in Rotating Shift Workers - A Randomised Controlled Feasibility Trial

The aim of this clinical trial is to assess whether it is feasible for shift workers to follow a time-restricted eating diet. The trial will investigate the impact of time-restricted eating on blood glucose levels during day and night shifts both with and without the time-restricted eating diet.

The trial aims are:

• Is it feasible for shift workers to adhere to a night time time-restricted eating protocol?
• How does time-restricted eating affect blood glucose levels during the day and night shifts and over the whole day?

Study Overview

• Status: Completed
• Conditions: Eating Behaviors; Shift Work
• Intervention / Treatment: Behavioral: Time Restricted Eating

Detailed Description

Shift work is an essential component of modern workforces, with about 20% of the workforce regularly engaged in shift work. Research has shown shift workers are at higher risk of chronic diseases, including cardiometabolic disease, compared to day-only workers. Specifically, evidence shows eating overnight significantly increases the risk of metabolic syndrome. We also know eating patterns of shift workers and non-shift workers are different with evidence from our research showing shift workers engaged in night shift change their eating behaviors compared to day shifts. With a substantial proportion of the workforce involved in shift work, understanding the health challenges is crucial for developing targeted interventions and promoting a healthier shift working population.

Despite the need for behavioural eating interventions in shift workers, there is a lack of studies examining how these eating interventions would be implemented in real world contexts. Some dietary interventions related to quantity, quality and timing of food in shift workers have been reported, including limiting the quantity of food with various macronutrient restriction and low-calorie meal replacements, improving the quality of food with dietary advice/counselling, and promoting healthier food choices with variable results.

With recent recognition of the timing of food consumption being an important factor of metabolic regulation, time restricted eating (TRE) offers a viable strategy for improving metabolic health. TRE is a chrono-nutritional strategy involving close alignment of meal timing with typical circadian physiology over 24-hour periods. Typically, this involves an eating window of approximately 8 hours, with no eating during the night. Evidence shows TRE improves alignment of the fasting/eating cycle with the central circadian pacemaker and initiating nutrient-sensing pathways to ensure nutrient homeostasis. Research has shown TRE is an effective chrono-nutritional intervention for weight reduction, improvements in HbA1c and insulin levels, reduced insulin resistance or enhanced insulin sensitivity, improved glucose tolerance and reduced mean fasting glucose and improved quality of life. However, using TRE has not been examined extensively in shift workers in real world settings.

A recent narrative review found only three studies had investigated TRE as a diet strategy for shift workers under real-life conditions and these studies were conducted in populations with limited exposure to shift work situations (e.g. rotating shift work). Therefore, research is required that investigates the feasibility of TRE during night shifts in rotating shift workers.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Australia
  • New South Wales
    • Caringbah, New South Wales, Australia, 2229
      • The Sutherland Hospital

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Healthcare professionals engaged in rotating shift work, including night shifts;
• Aged 23-60 years;
• At least 12 months experience in shift work;
• Willing to wear continuous glucose monitor sensors;
• Willing to engage in time restricted eating.

Exclusion Criteria:

• Diagnosis of diabetes (Type 1 or 2), any bariatric surgery, coeliac disease, inflammatory bowel disease, endocrine disorders affecting glucose metabolism, current or history of eating disorder, any liver, kidney, or coronary heart disease, obese (BMI>35) or underweight (BMI< 18) or any severe or unstable chronic medical conditions or cancers;
• Currently taking medications known to interact with glucose metabolism, i.e. thyroxin, insulin sensitizers, glucocorticoids, or anti-depressants, weight loss medication;
• Undertaking current structured or restrictive dietary plan;
• Shift workers who routinely do not eat between 23:00 and 06:00 hours during night shift;
• Current or planned pregnancy or currently breast feeding;
• Consume three or more standard alcohol containing beverages on a single occasion almost every day;
• People who identify as having significant caffeine dependency and are unwilling to limit intake of calorie free energy drinks;
• People with planned travel over time zones during the study period
• Any contraindication to use of Abott FreeStyle Libre Pro glucose sensor (eg prescription of vitamin C, Salicylic acid or paracetamol - to be reviewed by study clinician).

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Time Restricted Eating; Participants will follow a time-restricted eating diet during day and night shifts over 2 weeks	Behavioral: Time Restricted Eating; The intervention arm will consist of a time-restricted eating protocol with fasting between 11:00 PM to 6:00 AM. Ad libitum eating will be allowed outside these times and the protocol will be administered during day and night shifts over a 2 week period.
No Intervention: Control Arm; Participants will follow their usual eating patterns without restrictions during day and night shifts over 2 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Feasibility of time-restricted eating (TRE) among shift workers (Recruitment and Participation Rate)	Feasibility will be assessed through a composite of the following metrics: Recruitment and participation rate (%) will be assessed as the percentage of participants randomized from the screened population. Each component will be assessed separately but reported as contributing factors to the overall feasibility.	From enrolment to end of treatment at 2 weeks
Feasibility of time-restricted eating (TRE) among shift workers (Adherence Rate)	Feasibility will be assessed through a composite of the following metrics: Adherence rate (%) percentage of participants who comply with the TRE protocol over a 2-week period, determined using self-reports Each component will be assessed separately but reported as contributing factors to the overall feasibility.	Two weeks
Feasibility of time-restricted eating (TRE) among shift workers (Study Completion Rate)	Feasibility will be assessed through a composite of the following metrics: Study completion rate (%) percentage of participants who complete the 2-week study period without dropping out. Each component will be assessed separately but reported as contributing factors to the overall feasibility.	Two weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Blood glucose levels during the 2-week study period	Average 24-hour glucose levels;; Nocturnal glucose levels;; Sleep time glucose levels;; Day and night shift levels.	2 weeks
Facilitators and barriers associated with adherence to time restricted eating	Only in the intervention arm, participants will be asked questions about issues about eating patterns during the time restricted eating including barriers and facilitators for maintaining the fasting period.	2 weeks

Collaborators and Investigators

• Sponsor: Woolcock Institute of Medical Research
• Collaborators: South Eastern Sydney Local Health District
• Investigators: Principal Investigator: Christopher J Gordon, PhD, Woolcock Institute of Medical Research and Macquarie University

Study record dates

Study Major Dates

• Study Start (Actual): March 24, 2025
• Primary Completion (Actual): July 10, 2025
• Study Completion (Actual): September 1, 2025

Study Registration Dates

• First Submitted: November 4, 2024
• First Submitted That Met QC Criteria: November 11, 2024
• First Posted (Actual): November 13, 2024

Study Record Updates

• Last Update Posted (Actual): December 22, 2025
• Last Update Submitted That Met QC Criteria: December 15, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: feasibility; time restricted eating; dietary intervention; Shift Worker Health
• Additional Relevant MeSH Terms: Behavior; Behavior, Animal; Fasting; Feeding Behavior; Intermittent Fasting
• Other Study ID Numbers: 2024/ETH01526

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: All data will be dei-dentified using a unique study ID.

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