Estrogen, the main female sex hormone, plays a much larger role in a man’s libido than previously thought. Lowering estrogen in men on therapy for low testosterone leads to decreased libido and increased body mass, Joel Finkelstein, an endocrinologist, found in a study. This happens despite the increase in testosterone with the therapy, he points out in his publication in the New England Journal of Medicine. Estrogen is not just a “female” hormone and its balance in the male body is of great importance for good health. In the male metabolism, some testosterone is naturally converted to estrogen, but it is unstable and breaks down if testosterone is too scarce. Research proves that both sexes need endogenous hormones of the opposite sex to maintain a normal sex life. More than 300 men from 20 to 50 years of age were included in the study, in which the production of all sex hormones was interrupted by means of special therapies. Then half of them received a drug to increase testosterone production plus a placebo, and the other half received the same testosterone promoter plus a drug that suppresses estrogen production. The results show a significantly reduced libido in the first group and completely suppressed in the second. Finkelstein also concluded that testosterone is the main hormone determining the volume of active body mass and muscle strength, while estrogen causes fat accumulation. NEWS_MORE_BOX The specialist warns that testosterone preparations, nutritional supplements and ointments should not be used without a doctor’s permission. Many are based on synthetic hormones that cannot be fully metabolized by the body and converted into estrogen. This leads to an imbalance in favor of testosterone, which has already been proven to lower libido and cause erectile dysfunction, decreased muscle and bone mass, and depression.