The #1 Most Important Hormone for Men

Make no mistake, guys: Our manhoods are under attack. I’m talking about testosterone, the hormone that literally makes us men. Delivery of the right amount at the critical moment shifts development of a fetus away from the basic human blueprint, which is female, and onto the path to masculinity. A surge in testosterone (from the testes—hence the name) in adolescence boosts us into manhood.

And for the rest of our lives, testosterone—or the lack of it—plays a key role in muscle strength, lean body mass, bone density, mental sharpness, and libido. Heightened testosterone is also associated with self-confidence and social success. Low T, on the other hand, increases your risk of heart disease, prostate cancer, depression, diabetes, and stroke. Interesting fact: Despite its explosive reputation, there's no solid evidence that it causes aggression or violence. Who wouldn’t want more of a hormone like that?

Problem is, our testosterone levels are dropping—day after day, year after year, generation after generation. Most men can expect their levels to fall by about 1 percent a year beginning in their 50s. So a man in his 70s might have only half the testosterone he had when he was 25. But the researchers behind the Massachusetts Male Aging Study have noticed something strange. Men born more recently have lower T levels overall. In the study, 60-year-olds in 2003 had about 15 percent less testosterone than 60-year-olds in 1988, according to Thomas G. Travison, Ph.D., the lead author. Sixty is looking like the new 70. What’s happening?

One obvious explanation: We’re fatter now—studies show that if you gain 10 percent in your BMI, you can expect your testosterone to drop by about the same amount. But this alone can’t account for the precipitous drop in our T levels, says the researchers, who believe there are environmental factors at play. Fact is, many common lawn-care products and insecticides have been linked to lower testosterone levels.

As the research continues, one thing is certain: Testosterone is no longer just a hot topic for misguided weight lifters or baby boomers with delusions of eternal youth. It's something the average guy will need to think about at some point in his life. After all, a testosterone shortage could literally send you to an early grave. Follow these steps to lift your levels and lengthen your life.

1. Uncover Your Abs
As your waistline expands, your testosterone levels shrink. A 4-point increase in your body mass index—about 30 extra pounds on a 5'10" guy—can accelerate your age-related T decline by 10 years. If you’ve got 10, 20, or even 30 pounds to lose, try Belly Off! 2012, our free diet plan, exercise program, and community that will help you reach your goal weight without giving up the foods you love.

2. Build Your Pecs
Finnish researchers recently found that men who lifted weights regularly experienced a 49 percent boost in their free testosterone levels. "As you strengthen your muscles, the amount of testosterone your body produces increases," says David Zava, Ph.D., CEO of ZRT Laboratory. You need to push iron only twice a week to see the benefit, but the more vigorous your exercise, the bigger the benefit.Try this testosterone-boosting workout designed exclusively by Men’s Health’s experts.

3. Fill Up On Fat
Trimming lard from your diet can help you stay lean, but eliminating all fat can cause your T levels to plummet. A study published in the International Journal of Sports Medicine reveals that men who consumed the most fat also had the highest T levels. To protect your heart and preserve your T, eat foods high in monounsaturated fats—food such as fish and nuts.

4. Reduce Your Stress
Mental or physical stress can quickly depress your T levels. Stress causes cortisol to surge, which suppresses the body's ability to make testosterone and utilize it within tissues, says Zava. Cardio can be a great tension tamer, unless you overdo it. Injuries and fatigue are signs that your workout is more likely to lower T than raise it.

5. Sleep In on Weekends
A recent University of Chicago study found that getting only 5 hours of sleep—instead of the recommended 8 hours a night—can decrease T levels by 10 to 15 percent. That's because sleep deprivation also elevates cortisol levels. If you already have low testosterone, aim for 10 hours of shut-eye a night. If that's impossible, try slipping a 30-minute nap into your day.

6. Push Away from the Bar
Happy hour can wreak havoc on your hormones. In a recent Dutch study, men who drank moderate amounts of alcohol daily for 3 weeks experienced a 7 percent decrease in their testosterone levels. Limit your drinking to one or two glasses of beer or wine a night to avoid a drop in T.

7. Join a Team
This can be at work, or on a field or court somewhere. Yes, competing mentally or athletically boosts T levels, but studies also suggest that postgame bonding with teammates does the same. So while playing chess against a computer may give your T a lift, competing against a buddy—and bragging about your victory afterward—is even better.