In order to figure out how low testosterone changes a man’s body, the study team treated hundreds of guys with drugs that stopped production of all reproductive hormones—both testosterone and estrogen. The researchers then offered the men treatments that restored either testosterone and estrogen, or just T. Among the estrogen-deficient dudes, body fat accumulations were significantly greater—and both sexual desire and erectile function suffered—compared to men who received both T- and E-boosting drugs, the research shows. Put simply, several male problems doctors typically associate with low testosterone—problems like loss of libido, loss of bone, and weight gain—become worse when men lack sufficient amounts of estrogen, explains study coauthor Joel S. Finkelstein, MD, an endocrinologist at Mass General and corresponding author of the New England Journal of Medicine study. All men convert some of their body’s testosterone into estrogen. In fact, healthy older men have more than double the amount of estrogen found in post-menopausal women, Dr. Finkelstein says. But it still came as a surprise to the researchers that low-E would have such significant effects on men’s fat accumulation and sexual function—regardless of T levels, he adds. Should you worry about low E? For most men, the answer is no. Dr. Finkelstein says estrogen deficiency is usually seen only among prostate cancer sufferers treated with hormone suppression drugs. For those men, testosterone-boosters aren’t an option because they would interfere with the cancer therapy. But estrogen-boosting treatments might help these cancer sufferers ward off fat accumulation and loss of sex drive, he adds. Bottom line: Men rely on estrogen as well as testosterone to remain physically fit and healthy. And this new understanding of estrogen’s importance may help doctors develop therapies to combat age related body changes and loss of sexual function among men, the Mass general research suggests. More from Prevention: How Your Hormones Affect Your Weight
