Study of Safety, Tolerability, and Pharmacokinetics of REGN2477 Alone and in Combination With REGN1033 in Healthy Postmenopausal Women and Healthy Adult Men

Key Inclusion Criteria: * Postmenopausal women age 45 to 70 years and age 35 to 60 years inclusive for men not intending to father children * BMI between 18 to 32 kg/m2, inclusive * Willing and able to maintain current diet, supplements and physical activity level throughout the study * Provides signed informed consent Key Exclusion Criteria: * Significant illness or history of significant illness * Contraindication to MRI * History of human immunodeficiency virus (HIV); hepatitis B or hepatitis C virus (HCV) * History of immobilization, major surgical procedure, fracture, or major trauma within 9 months prior to screening * History of significant gynecological disorders or malignancies; history of breast malignancies (uterine fibroids or dysfunctional uterine bleeding is acceptable) * Inconsistent vigorous physical activity (on fewer than 5 days per week), such as intermittent weight lifting * History of hypersensitivity reactions to tetracycline antibiotics (includes doxycycline), vaccines, or biologics * Use of agents that alter muscle mass that have not been at a stable dose for 3 months prior to screening (includes protein supplements), or use of any weight altering or anabolic steroid drugs (includes drugs for obesity, diuretics, testosterone) * Participants treated with a biologic therapy or biologic immunotherapy in the previous 12 weeks prior to screening and during the study Note: Other protocol Inclusion/Exclusion criteria apply.