Dr. William David Stinson, M.D.

Your body forms three types of estrogen: estradiol, estriol, and estrone. The first two come from the ovaries. Estrone is created by fat in the body via conversion of androstendione produced by the adrenal glands. In a normal menstrual cycle, your body produces little to no estadiol and estriol while menstruating. Then, in the first two weeks after the beginning of your period, these to estrogens emitted from the ovary increase and produce the lining needed to support a pregnancy and encourage the development of an egg to be released at ovulation. A spike in estrogen occurs at approximately 14 days causing the release of the egg. At this point, the corpus luteum develops on the ovary and produces progesterone. Meanwhile body fat continues to produce a continuous and constant supply of the weaker estrogen, estrone. Progesterone secretion continues for the next 2 weeks in anticipation of a pregnancy. If pregnancy does not occur, then the body stops producing ovarian estrogens and progesterone. This lack of hormones causes the uterus to lose the lining needed for pregnancy and start the cycle all over. The problem with excess weight is that estrone,
produced by body fat, remains constant. This estrogen can become significant enough to prevent the withdrawal bleeding expected from the lack of ovarian produced estrogen and progesterone. In addition, this excess hormone can result in a much thicker uterine lining to shed each month. Therefore, many women with excess weight can find that they miss periods from the lack of hormone withdrawal or have much heavier periods from excess growth of uterine lining to shed.

W. David Stinson, MD