This page is catered to elucidating metabolic differences between men and women (specifically concerning what affects women, or what does not differ) and may address some issues that are exclusively feminine in nature such as exercise and pregnancy.
Anatomical and sexual differences will not be discussed unless needed.
When carbohydrates are ingested during sub-maximal exercise (67% VO2 max), the bodies expected response of using more glucose for energy in lieu of fatty acids does not differ significantly between the genders, although a trend is shown for females to use more ingested carbohydrate as fuel rather than stored carbohydrate (glycogen) relative to males.
Along the lines of lower carbohydrate utilization, females tend to also have a reduced Respiratory Exchange Ratio (RER), indicative of less carbohydrate utilization. A trend of carbohydrate preservation in the face of metabolic stress exists in females.
In the fasted state, women also tend to burn more fat as a percentage during endurance exercise although overall calories do not differ.
Women have a higher estrogen to testosterone ratio than men.
This higher ratio may be a reason why more fatty acids are used for energy rather than carbohydrates or amino acids at rest and exercise. This is an effect of estrogen per se, and occurs in men supplemented with estrogen as well. In experiments with rats, a trend of estrogen inducing preferential fat loss over glycogen usage is evident.
Along the lines of the aforementioned preservation of carbohydrate in the face of metabolic stress, these reactions may also be mediated by estrogen. Experimental models of animals show females having a higher survival rate during experimentally induced diabetes and a line of genetic knockout mice (mice lacking PPARa genes) had complete death of males by hypoglycemia, and only 25% females death; some males survived with estrogen administration. Estrogen may theoretically be useful in protecting from nonketotic hypoglycemia and rhabdomyolysis, but may inadvertently reduce overall carbohydrate usage for fuel and subsequent performance capabilities.