Inclusion Criteria:  Age 60 years and over Ability to provide informed consent Willing to accept random assignment to condition Body mass index <40 kg/m2 Weight stable in the prior 3 months (<2 kg weight change) and willing to remain weight stable throughout the study Free from alcohol dependence or abuse, Mini-mental stage examination score ≥21  Exclusion Criteria:  Uncontrolled thyroid disease Regular vigorous aerobic (>6 bouts/week, >60 min/bout at a workload >6 METS) Blood donation within 8 weeks prior to enrolling in the study