Effects of aging on resting metabolic rate: A systematic review and meta-analysis

Objective. To meta-analyze previous literature in order to find a consensus regarding aging effects on resting metabolic rate (RMR) and to identify the main players in this process. Methods. Through a search on PubMed eighteen trials comparing RMR between older and young adults were included for meta-analysis. Results. Older adults had significantly lower RMR than young adults (-437 kJ/d [-591; 283], p<0.001). While older men had a reduction of -725 kJ/d ([-1068; -382], p<0.001), older women had just less than half of this reduction (-233 kJ/d [ -308; -158], p<0.001). The age induced-RMR reduction was predicted by muscle mass difference between groups (r2=0.55), but not by body mass or other body composition components. Conclusion. RMR is indeed reduced in older adults and muscle mass loss is the main player in this process. Future studies should investigate how much of this reduction can account for poor health conditions in older adults.