Time-Restricted Eating and Exercise for Bone Health (OSTEO-FIT)

Inclusion Criteria:

• Men and women aged 50-75 years with body mass index (BMI) >25kg/m2
• Osteopenia, defined as a T score between -1.0 and -2.5 at the lumbar spine, femoral neck, or total hip
• Elevated adiposity, defined by waist circumference >102 cm in men or >88 cm in women
• Stable health history over the past 2 months
• Stable medication history over the past 2 months, as recommended by the primary provider
• Willing and able to provide informed consent

Exclusion Criteria:

• Participation in a formal weight loss program, intentional caloric restriction, fasting >10 hours/day, or ≥10 pounds weight loss within the past 3 months
• Current participation in structured exercise training, supervised rehabilitation, or >150 minutes/week of moderate intensity physical activity
• Medical conditions or use of medications affecting bone metabolism
• Diagnosed diabetes or use of insulin or glucose lowering medications
• Resting heart rate >120 beats/minute or daytime blood pressure ≥180/100 mmHg
• Unstable angina, myocardial infarction, or stroke within the past 3 months
• Continuous supplemental oxygen use for chronic pulmonary disease or heart failure
• Rheumatoid arthritis, Parkinson's disease, dialysis, active cancer treatment within the past year, or diagnosed cognitive impairment
• Absolute contraindications to exercise training according to American College of Sports Medicine guidelines
• Unable to fast for 16 hours
• Any condition that in the opinion of the investigator would impair ability to participate in the trial