More accurately, metabolism is used as a general term for all chemical reactions in the body that manage material and energy. There's anabolism, in which energy is consumed to synthesize complex molecules from simpler ones, and then catabolism, in which energy is created by the breakdown of complex molecules to simpler ones. Our "metabolic rate" or what we refer to as metabolism combines both of those to get an energy reading of the total anabolic pathways in our body!
School lesson aside, a study in 1997 found that postmenopausal women had a HIGHER energy expenditure than premenopausal women, however once activity level and body composition was taken into effect, there was no significant difference- meaning that the study supported *no change* in metabolic rates. I'll keep searching for more reports for you and let you know if I find any!