Progestins , the most important of which is progesterone , are the other type of female sex hormone and are named for their role in maintaining pregnancy (pro- gestation ). Estrogens and progestins are secreted cyclically during menstruation . During the menstrual cycle , the ruptured ovarian follicle (the corpus luteum ) of the ovary produces progesterone, which renders the uterine lining receptive to the implantation of a fertilized ovum . Should this occur, the placenta becomes the main source of progesterone, without which the pregnancy would terminate. As pregnancy progresses, placental production of progesterone increases, and these high doses suppress ovulation , preventing a second conception . The contraceptive quality of progesterone led to the development of structurally modified progestins and estrogens—the oral contraceptives known as birth-control pills, used by women to prevent unwanted pregnancy.
Beth maybe based upon today's standards……but I am talking about our biologic standards. Most people reading this are coming to the understanding from their own perception of what fat really is. Leptin became biologically important from an evolutionary standpoint because food was scarce more often then not and most humans had to protect against low leptin levels not high one like we see today. The paradox in this system and why people get confused is that ultra low leptin and ultra high leptin biochemically cause high US CRPs and this shuts down the thyroid. It is protective in food shortage for survival and it kills you with chronic excess due to chronic elevations of cortisol and insulin simultaneously present in the cellular terroir (levee one). This induces mRNA at the DNA level that up-regulates genes that no longer allow p53 gene to protect our genome from oncogenesis. (levee 16)