Much of this site focuses on ways to increase testosterone. But this emphasis on testosterone can be somewhat misleading for some men, because it implies that testosterone is the only hormone in any of the problems they might be experiencing. In reality, there is another major player, especially for overweight, middle-aged and steroid-using guys.
In fact, it is interesting that some middle aged and beyond males have normal testosterone yet they have most of the symptoms of andropause or low testosterone. How can this happen? Because, more often than not, males with normal testosterone and andropause symptoms have overly high estrogen levels. The reason is simply that it is the ratio of testosterone to estrogen that is ultra-critical for us guys and so increased estrogen can be just as physiologically negative for us as low testosterone.
It may surprise you to know that testosterone and estrogen are actually chemically very similar: they differ by only a carbonyl and a methyl group. But, oh, what a difference a subtle chemical alteration can make! Testosterone is responsible in us guys for a bigger larynx, thicker hair shafts, larger organs, augmented bone density and other traits that differentiate us from members of the fairer sex. In contrast, estrogen in females leads to breast development and enlargement, less body hair and a more nurturing attitude.
The problem for us males is that increasing estrogen can lead to decreased libido and erectile strength. In other words, too much estrogen can literally turn you into a girly man and take your sexual legs right out from under you. As you may know, estrogens are even associated with the "man boobs" that you see many overweight, middle aged guys struggling with. Yes, you have got to get estrogen under control!
So why do estrogen levels increase with age? Researchers have observed is that, in general, adipose fat levels increase with aging while muscle mass decreases.  As we have mentioned elsewhere, this increase in fat tissue results in increasing tissue levels of aromatase which converts testosterone to estrogen. In fact, this conversion of testosterone is the only reason we males have any estrogen. But this increased conversion to estrogen leaves us with less testosterone which decrease our muscle mass which makes it easier for us to gain weight and on and on the cycle goes.
NOTE: This is yet another reason why exercise is even more critical as we age: it preserves (or even builds) muscle mass and burns off fat at the same time.
So notice that one of the ugly facts of middle age is this rise of aromatase leads to a simultaneous decrease in testosterone and increase in estrogen. The sword cuts both ways one might say. Woe is us because we are simultaneously stripped of our primary male hormone and injected with the primary female hormone. And that means both numerator and denominator move in the wrong direction in the all important ratio of testosterone/estrogen.
This, by the way, leads to a perilous tissue accumulation of estrogen. Researcher have discovered this in the prostate.  In fact, that same study concluded that "the prostatic accumulation of DHT, estradiol, and estrone is in part intimately correlated with aging". Estradiol and estrone are two forms of estrogen, neither of which do you want accumulating in your tissues. In other words, male menopause or andropause is as much about estrogen as it is about testosterone.
I should mention, though, that some estrogen is essential for bone health. In fact, one of the major issues that low testosterone males can have is also having low estrogen (since estrogen is made from testosterone). Low estrogen, at least in the long term, will actually lead to osteoporosis which is yet another reason to keep your testosterone up through HRT (Hormone Replacement Therapy).
Do you know the foods and drinks that boost Nitric Oxide and repair the veins and artieries to your penis? Then check out the Peak Erectile Strength Diet Program where I show you how to dramatically improve your erectile strength.
That said, we males only need small and youthful amounts of estrogen for optimum health. The overabundance of estrogen in middle and old age is simply a bad dream. Here are just a few of the nasty things estrogen can do to us:
So how can you keep the female hormone in check? Read my links on How to Control Estrogen. You should also ehck out How to Increase Your Estrogen (Estradiol) Levels as well for some of the good, bad and ugly things that can increase T and E2.
2) Medical Hypotheses, Jun 2001, 56(6):702-708, "Aromatase, adiposity, aging and disease. The hypogonadal-metabolic-atherogenic-disease and aging connection"
12) J Clin Endocrin Metab, 1993, 77: 375-381, "Effect of aging on endogenous levels of 5-alpha-dihydrotestosterone, testosterone, estradiol and estrone in epithelium and stroma of normal and hyperplastic human prostate"