How do the hormones of the endocrine system act as a feedback mechanism for the menstrual cycle?

In positive feedback, rising levels of hormones feedback to increase hormone production. During most of the menstrual cycle, estrogen and progesterone provide negative feedback to the hypothalamus and pituitary gland. This keeps their levels more or less constant.

In negative feedback, rising levels of hormones feedback to the hypothalamus and pituitary gland to decrease the production of the hormones. In positive feedback, rising levels of hormones feedback to increase hormone production. During most of the menstrual cycle, estrogen and progesterone provide negative feedback to the hypothalamus and pituitary gland. This keeps their levels more or less constant. During days 12–14, however, estrogen provides positive feedback to the hypothalamus and pituitary gland. This causes a rapid rise in the production of estrogen by the ovaries and leads to ovulation.

Food energy is potential energy (because it needs something done to it, in this case breaking down) and it is stored in a chemical form.