BMJ openJun 17, 2021

10-Hour Time-Restricted Eating and Heart Health Risks in Firefighters Working 24-Hour Shifts: A Feasibility Trial

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Updated Mar 30, 2026

Abstract

This study involves 150 firefighters participating in a trial to assess the impact of a 10-hour (TRE) regimen on health parameters associated with cardiometabolic disease.

Chronic circadian rhythm disruption in firefighters is linked to increased risk of cardiometabolic disease.
Preliminary studies suggest that time-restricted eating may help regulate circadian rhythms and reduce disease risk.
The intervention group will follow a 10-hour eating window, while the control group will receive standard Mediterranean diet counseling.
Health parameters being evaluated include blood glucose levels, body weight, body composition, and various biomarkers related to metabolism and inflammation.
Assessments will occur at multiple time points throughout the year, including after a 3-month monitored period and subsequent follow-ups.

Simplified

INTRODUCTION: Career firefighters experience chronic circadian rhythm disruption, increasing their risk of cardiometabolic disease. The recent discovery that eating patterns regulate circadian rhythmicity in metabolic organs has raised the hypothesis that maintaining a consistent daily cycle of eating and fasting can support circadian rhythms and reduce disease risks. Preclinical animal studies and preliminary clinical trials have shown promising effects of (TRE) to reduce disease risk without compromising physical performance. However, there is a lack of research on TRE in shift workers including firefighters. This study aims to investigate the feasibility and efficacy of 10-hour TRE on health parameters that contribute to cardiometabolic disease risks among career firefighters who work on a 24-hour shift schedule.

METHODS AND ANALYSES: The Healthy Heroes Study is a randomised controlled parallel open-label clinical trial with 150 firefighters over 1 year. Firefighters are randomised with a 1:1 ratio to either the control or intervention group. The control group receives Mediterranean diet nutritional counselling (standard of care, 'SOC'). The intervention group receives the same SOC and a self-selected 10-hour TRE window. After the 2-week baseline, participants enter a 3-month monitored intervention, followed by a 9-month self-guided period with follow-up assessments. The impact of TRE on blood glucose, body weight, body composition, biomarkers (neuroendocrine, inflammatory and metabolic), sleep and mood is evaluated. These assessments occur at baseline, at the end of intervention and at 6, 9 and 12-month follow-ups. Temporal calorie intake is monitored with the smartphone application myCircadianClock throughout the study. Continuous glucose monitors, wrist-worn actigraphy device and questionnaires are used to monitor glucose levels, activity, sleep and light exposure.

ETHICS AND DISSEMINATION: The study was approved by the Institutional Review Boards of the University of California San Diego and the Salk Institute for Biological Studies. Results will be disseminated through peer-reviewed manuscripts, reports and presentations.

TRIAL REGISTRATION NUMBER: NCT03533023; Pre result.

Key numbers

150

Sample Size

Total number of participants in the study.

20%

Dropout Rate

Anticipated percentage of participants who may not complete the study.

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10-Hour Time-Restricted Eating and Heart Health Risks in Firefighters Working 24-Hour Shifts: A Feasibility Trial

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