Inclusion Criteria:  Healthy young (age: 18-35 years) or older (age: 60-80 years) adults Average daily step-count >7,000/day BMI between normal to overweight (18.5-29.9 kg/m2)  Exclusion Criteria:  Regular use of nonsteroidal anti-inflammatory drugs (with the exception of daily low-dose aspirin) Use of anticoagulants Use of a walker, cane, or assistive walking device Current or recently remised cancer Infectious or gastrointestinal disease Inability to comply with study protocol (e.g., >2,000 steps/day during Step-Reduction Phase) Regular tobacco use Self-reported illicit drug use (e.g. growth hormone, testosterone, etc.) Diagnosed chronic illness (e.g. type 2 diabetes, heart disease, thyroid disease) Pregnant Hormonal Replacement Therapy