Metabolism 101

The San Francisco Chronicle reports:

Total metabolic rate (TMR), which represents your total daily caloric needs, is made up of three major components: resting metabolic rate, thermic effect of activity and thermic effect of feeding. Resting metabolic rate (RMR) accounts for the greatest share of TMR, approximately 60 to 75 percent, and includes the energy used to keep your major organs running. Genetics plays a small role in RMR (about 10 percent), but most of the variability in RMR is dependent on three factors: age, sex and fat-free mass (muscle, bone, water). While you can't control your age or sex, you can control your fat-free mass. Beginning at age 30 or so, RMR drops by about 3 percent per decade, mainly due to a drop in muscle mass. But this drop in muscle is partially preventable with strength training, which is why it is one of the most important things that you can do to increase, or at least limit the decrease, in metabolism.

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