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Flip open a magazine, turn on the television or surf the Web, and within seconds you’ll encounter imagery designed to raise the mercury in your thermometer. Sex is used to sell everything from motor oil to phone books, and fashion trends unravel evermore threads of women’s clothing.

One of the first realities to be aware of is that Madison Avenue is probably more sex crazed than you are. A man’s libido may simply not be able to keep pace with the onslaught of innuendo in advertising, and recognizing this may actually provide some relief. Nonetheless, sex can be incredibly preoccupying. If sexual energy could be rerouted to another part of the brain, the average guy would probably be able to understand metaphysics and solve the square root of pi.

But what is “enough” sex? Should a man of any age worry if his sexual engine slips from fifth gear into neutral?

“Libido is often thought of as a single-person event, but it’s really a couple-related phenomenon,” says Dr. Harry Fisch, a leading New York urologist and author of The Male Biological Clock. “Someone who’s older and having sex once a month might not complain about not having enough sex. But the person who might complain is the wife or girlfriend. It’s a relationship, and it takes two.”

Diagnosing the Dip

If you and your partner do suspect that your libido is not all it could or should be, a low testosterone level is the likely culprit. Testosterone is the hormone most responsible for male characteristics such as muscle development and facial hair as well as aggression, competitiveness and sexual drive.

It’s common and natural for testosterone levels to drop by 1 percent to 2 percent every year beginning at age 30. The dwindling supply of male sex hormones, or androgens, is known as andropause, a kind of equal-opportunity name for male menopause. Or, as Dr. Fisch calls, it, menoporsche. “I call it ‘menoporsche’ because I’ve seen guys who think buying a hot new car like a Porsche will give them a shot of sex appeal or attractiveness,” he laughs, “when in fact they’d be much better off getting their testosterone level checked.”

Some men produce low levels of testosterone even before the age of 30. Regardless of age, one result of this condition, known as hypogonadism, is decreased libido. The condition is treatable. Testosterone replacement therapies introduce more of the hormone to a body that could not supply enough on its own. Another method is anti-estrogen therapy: Just as women have small amounts of testosterone, men have small amounts of the female hormone, estrogen. Anti-estrogen therapy helps re-establish an appropriate balance. Of course, all such options should be discussed with a qualified urologist, since there are risks and side effects.

The best option, however, is to get the body to produce more testosterone on its own. Before you even consider medical alternatives, there are several avenues to explore. And the first thing you can do is …