Answer
Monica has been exercising excessively. One of the results of this is that she has lost a large amount of body fat. Too much body fat is undesirable, but too little body fat can impair or cause the inhibition of certain physiological/metabolic processes , especially in women. A certain amount of body fat is essential to permit the adequate of female hormones --estrogens and progesterone. These hormones are necessary in certain amounts for the maintenance of the ovarian cycle. Monica is not secreting adequate amounts of estrogen and progesterone and this is the cause of her amenorrhea.
Work Step by Step
Monica's hypothalamus is not producing enough gonadotropin releasing hormones/factors, consequently her anterior pituitary (AP) production of follicle stimulating hormone (FSH) and luteinizing hormone (LH) have decreased below normal levels. Because not enough gonadotropins is available, the follicles and the ova have failed to restart their development to maturity. Therefore, there is no ovulation. Because there is no ovulation and no mature, secreting ovm the plasma levels of estrogen and progesterone have fallen. As a consequence, the the hormonal feed-back loop to the hypothalamus failed -- so there is little or no GnRH secretion , little or no LH and FSH secretion, and normal cycling failed because there is no follicle cohort progression, no ovarian maturity, and ovulation.
If Monica cuts down on her extremely vigorous exercise regime and eats a diet with a more fats, her weight will return to normal, her amount of body fat will increase, and her normal ovarian cycling will resume.
