The assessment of vertebral bone marrow water-fat composition is attracting growing interest for applications in osteoporosis and bone metabolism. Chemical shift encoding-based water-fat MRI allows spatially resolved assessment of proton density fat fraction (PDFF) at the spine. This study demonstrated that males started with greater PDFF values in the Twenties compared to females. However, females showed an accelerated bone marrow fatty conversion until the Seventies on. This finding can be explained by the (patho-)physiological process of menopause. Interestingly, the relative age-related PDFF changes from the Twenties to the Seventies were dependent on the anatomical location and were most pronounced at lower lumbar vertebral levels in both genders.