What is the main explanation for the difference in basal metabolic rates between males and females of the same body weight?

Male have higher teststerone

Explanation:

Basal metabolic rate is the calories required by a person at rest. This energy is used endothermically by body in maintaining variuos mechanisms such as breathing, blood circulation and liver functioning.  More a person is active more will be the energy requirement.

Males have higher basal metabolic rate than females because of higher concentration of testosterone. Testosterone helps in building muscle. More the muscles a person have more will be his basal metabolic rate.

While females have less testosterone and higher proportion of fat cell in body and thus have lower metabolic rate.