Estrogen deficiency in men can cause increased body fat and diminished sexual function, according to the Los Angeles Times. Low estrogen levels may also cause bone loss, says Men's Journal. Estrogen is often called the female hormone because women produce more of it in proportion to testosterone while the opposite is true for men.
Low levels of the sex hormones estrogen and testosterone both negatively affect a man's libido and ability to have erections, notes WebMD. The male body converts some of the testosterone it produces into estrogen, so falling testosterone levels contribute to low estrogen. Healthy male adults have higher estrogen levels than menopausal women, says The New York Times. A New England Journal of Medicine study found that male sexual symptoms such as low libido and erectile dysfunction were most pronounced in men with a combination of low testosterone and low estrogen, reports the Los Angeles Times.
Low estrogen is particularly correlated with an increase in male body fat, states WebMD. In rodent studies, rats that had their estrogen receptors blocked gained fat. Estrogen appears to regulate how the body accumulates fat, according to The New York Times. Even men with sufficient testosterone and low estrogen levels gained fat in the New England Journal of Medicine study.