"F!reF!ghterF!t": Lifestyle Coaching Interventions for Obese Firefighters (FireFit)

Inclusion Criteria: * Male firefighters aged 18-60 years * Currently active as volunteer or career firefighters * Body mass index (BMI) ≥30 kg/m² based on self-reported height and weight * Express interest in participating in a clinical study aimed at improving body composition (weight loss), metabolic status, and quality of life * Residing and/or working in Massachusetts, Rhode Island, or Southern New Hampshire (Boston metro area) Exclusion Criteria: * Female sex\* * BMI \<30 kg/m² based on self-reported height and weight * Active psychosis * History or diagnosis (during the RCT) of any of the following: Major cardiovascular disease event (e.g., myocardial infarction, cardiac arrest, cerebrovascular accident) Cancer (excluding non-melanoma skin cancer) Abnormal liver function (aminotransferase, bilirubin, or alkaline phosphatase ≥3× the upper limit of normal) Renal dysfunction (estimated glomerular filtration rate ≤30 mL/min/1.73 m²) * Current or recent (within 6 months) use of testosterone treatment or anti-obesity/obesogenic medications * Unwillingness to adhere to potential intervention assignments * Because this is an exploratory study, the number of subjects is limited, and men make up roughly 85% of the US fire service, the current proposal is limited to men. In future studies, we will include women firefighters.