Estrogen is the female sex hormone, there are three major estrogens that occur in the body they are called estrone, estradiol, and estriol. Men also produce estrogen but in far smaller amounts. When women reach the age where they are ready to have children their estrogen levels rise, this causes the development of breasts and the start of the menstrual cycle.
Women produce most of their estrogen in the ovaries, and the adrenal glands, men produce a much smaller amount in the adrenal glands and they also produce some in the testicles. Too much estrogen can become a problem for both men and women, and a lot of male bodybuilders devote a lot of time to lowering their testosterone using drugs.
But estrogen has many uses, and it really should only be lowered if the amount is too high (something that happens to anyone who takes high levels of testosterone injections). Estrogen can increase metabolism, is responsible for protein synthesis in women, increase good cholesterol and lower bad cholesterol, and improve lung function.
The main role of estrogen is to enhance female characteristics, something that makes women look more feminine and something that most men want to avoid at all costs! It can widen hips, create breasts, and interestingly it is better at protecting the heart. This is why women are less likely to suffer from heart disease.
As we mentioned earlier men do produce small amounts of estrogen naturally and on the whole this is a good thing. The body tries to maintain the levels of both testosterone and estrogen, so that if one goes up the other will too. It is for this reason that bodybuilders can end up with very high levels of estrogen in their body.
If you were to artificially increase your bodies testosterone levels to ridiculously high levels so that you could pack on lots of muscle, lose fat, and get ready for a show, your body would start to increase the production of estrogen to try and re-balance the ratio. It would also release an enzyme called aromatase which is designed to turn excess testosterone into estrogen.
When the bodybuilder is artificially increasing their testosterone levels their body stops producing any of its own. Once the show is over the body has:
Because of this, lots of bodybuilders who don’t know what they are doing can end up with elevated estrogen levels. It is important for bodybuilders and generally any male with high estrogen levels to do simple activities that will lower estrogen. High levels will lead to the development of breast tissue, increased body fat storage, and a host of other issues that they’d rather avoid.
Another way that men can begin to produce more estrogen is to increase their body fat levels. Leading a largely sedentary lifestyle whilst eating a high calorie diet can lead to a lot of weight gain . For a man to lower their estrogen they need to focus on losing weight, eating foods that can help to block aromatase (the enzyme that turns testosterone to estrogen), and potentially look for some estrogen lowering supplements.
 Schneider, G., Kirschner, M., Berkowitz, R., Ertel, N. 1979. Increased estrogen production in obese men. The Journal of Clinical Endocrinology & Metabolism 48(4): 633-8