|This article does not cite any references or sources. (March 2011)|
Chronological age is your age in calendar years. Basal metabolic rate is the amount of energy consumed per unit of time when all environmental factors are considered neutral, the digestive system is in a post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans), and the energy expenditure is only sufficient to support normal functioning of the vital organs, the heart, lungs, nervous system, kidneys, liver, intestine, sex organs, muscles, and skin. Formulas for calculating basal metabolic rate take into account age, weight, height, activity level, body fat mass, and lean body mass.
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.
An individual's metabolic age will vary depending how their calculated basal metabolic rate compares to others of the same chronological age. Metabolic age is a new term used in the health and fitness industry to describe overall fitness and metabolic activity. Examining metabolic age will give insights to the overall level of health and wellness in comparison to those of the same age. Improving personal fitness is a main concern of most health-conscious individuals.:
Metabolic age is a reflection of physical health in the form of a calculation based on the base metabolic rate (BMR). If someone's metabolic age is lower than his or her actual age, it suggests that the body is in good health, while a metabolic age higher than the actual age indicates that someone may be experiencing health problems. This measurement is one among many which can be used to assess health, and people should avoid putting too much weight on it; a more complete assessment of physical health can be obtained from a doctor, who may also have suggestions to improve health.