Several factors can influence a person's metabolism, including genetics, age, sex, and muscle mass. Typically, individuals with higher muscle mass have a faster metabolic rate because muscle tissue requires more energy to maintain than fat tissue. Additionally, age-related declines in muscle mass can slow metabolism. Hormonal levels, particularly those associated with the thyroid and insulin, also play a significant role. Lifestyle factors, such as physical activity, nutrition, and overall energy balance, further impact metabolic function, affecting how efficiently the body converts food into energy.