All the components in the body require various levels of energy to be maintained. Body fat requires much less energy than lean muscle, as lean muscle is much more metabolically active and therefore requires more energy expenditure to remain in homeostasis. If comparing two individuals, with all variables being equal, the person with more lean muscle mass will have a higher basal metabolic rate, and therefore, a lower metabolic age in comparison to those with the identical chronological age.
According to a sports medicine specialist, "Metabolic age isn’t something we talk about in the medical community... The marker of the ultimate definition of health it is not.”
- "Metabolic Age: What It Is and What It Means For Your Health". Retrieved 2020-12-29.
- Anderson C, Sloan A, Dupree L, Walker B (June 2019). "Younger Relative Metabolic Age Is Associated with a More Favorable Body Composition and Plant-based Dietary Pattern (P21-038-19)". Curr Devel Nutr. Jun (3(Suppl 1)). doi:10.1093/cdn/nzz041.P21-038-19.