Final answer:
The body's metabolic rate is most significantly influenced by the amount of lean body tissue, as it is more metabolically active than fat tissue and burns more calories at rest. Men often have a higher basal metabolic rate due to greater lean muscle mass. However, height and age also play roles, with taller individuals and younger people generally having higher metabolic rates.
Step-by-step explanation:
The body's metabolic rate is influenced by various factors, including age, gender, activity level, and body composition—particularly the amount of lean body tissue. Among these, the amount of lean body tissue has the most significant influence on metabolism. This is because lean body mass, which includes muscle tissue, is more metabolically active than fat tissue, meaning it burns more calories at rest. Additionally, with aging, there is a decrease in metabolic rate by about 2 percent per decade after age 30 due to the loss of muscle mass. Men typically have more lean muscle mass than women, resulting in a higher basal metabolic rate. However, factors such as exercise can increase lean muscle mass and thus enhance metabolic rate.
Height can also affect metabolic rate because taller individuals have a greater body surface area and, therefore, a higher basal metabolic rate. This difference in BMR can result in weight differences when diets are not adjusted for height. Nevertheless, the amount of lean body tissue remains the predominant factor influencing metabolism over other variables.
It is worth noting that the metabolic rate is also a function of genetic factors, as proteins and enzymes derived from one's genetic background play a significant role in one's inherent metabolic processes. Despite this, the same overall metabolic processes occur in every individual's body.