The Healthy Heroes Study

Participants will be randomly assigned to a control group of behavioral nutrition counseling (standard of care) or the intervention group of standard of care with the addition of adopting a 10 hour eating window for one year (TRE). For the first 3 months of intervention, participants will be monitored closely by the research team. For the following 9 months, participants will be in a self-monitored intervention period. Investigators will evaluate the impact of TRE on blood glucose levels, biomarkers, sleep/mood, and weight loss. These assessments will be made at baseline, at the end of the 12-week monitored intervention period, and every 3 months (months 6, 9, and 12) during the self-monitored intervention period for one year. Food/drink intake, activity, and sleep will be monitored with the smartphone myCircadianClock application ("mCC app") throughout the study. A continuous glucose monitor, a wrist-worn actigraphy device, and questionnaires will also be used during the study.

As per recommendations from the fire department, fire department unions, and funding agencies, we did not require compromised health measures (e.g. hyperglycemia, hypertension, etc.) as inclusion criteria for they would be discriminatory against some firefighters.

Inclusion criteria

• Firefighter or work a 24-hr shift schedule with San Diego Fire and Rescue
• Age: 21-65 years
• Own a smartphone (Apple or Android Operating System)
• If participants are on cardiovascular medications (HMG-CoA reductase inhibitors (statins), other lipid modifying drugs (including over the counter drugs such as red yeast rice and fish oil), anti-hypertensive, anti-diabetes drugs), no dose adjustments will be allowed during the study period

Exclusion criteria

• Insulin-dependent diabetes mellitus
• Presence of acute chronic inflammatory or autoimmune disease (defined by acute symptoms or C-reactive protein >10 mg/L), malabsorption syndromes, liver disease, or kidney disease (stage 3 or greater)
• Uncontrolled thyroid disease
• Intake of drugs likely to interfere with study endpoints, including corticosteroids, anabolic steroids, anti-psychotics, antiretroviral drugs, and immunosuppressive drugs (within 3 months of starting the study)
• Presence or recent history of anemia (hematocrit <33% within 3 months of starting the study)
• History of bariatric surgery
• Pregnant or breast-feeding women
• Current or recent (within 12 months of starting the study) pregnancy or breastfeeding, or intention of becoming pregnant in the next 6 months
• Any cancer other than non-melanoma skin cancer in the last 3 years
• On a special or prescribed diet for other reasons (e.g. Celiac disease)
• Depression determined by the Beck Depression Inventory (BDI)
• Planned international travel during study period
• Insufficient logging on the mCC app (does not log at least 2 entries a day for 10 of 14 days) during baseline will exclude from being randomized into the intervention period