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 time-restricted eating (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.
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