Exercise, a healthy diet and sleep are three of the best ways to naturally boost testosterone, especially if you're out of shape. Excess body fat can decrease testosterone.
But don't starve yourself; then the body thinks you don't want to reproduce in a famine and shuts down testosterone production. "If you are overweight and have low testosterone levels, losing 5 to 15 pounds will help," said Anawalt. In general, the more aerobic exercise the better, but ultra-endurance athletes can see their testosterone levels decline.
Men who suffer from sleep apnea can have low testosterone; but giving these men supplements will make the sleep apnea worse. (Instead, sleep apnea is often treated using mild air pressure to keep the airways open).
If a man has concerns about his wellness or vitality, he should speak with his doctor before buying into the latest marketing surrounding "low T."
"Much of what you see on the Internet promulgated in ads is one giant hoax," Anawalt said. "What's lost in that is there really are men with low testosterone levels who have health consequences and need to be treated."
Still, that portion is small, he said. "I would liken it to the very profitable skin cosmetics industry which sells anti-aging cream," he said. "If it really worked, the whole world would be using it."
Testosterone levels throughout a man's life
Before birth: Testosterone and a product of its metabolism, dihydrotestosterone, cause the male genitalia to form.
Birth to 4 months: Testosterone levels continually high
4 months to onset of puberty: Levels drop and remain low
Puberty (age 12): Giant fireworks of testosterone. Testicles begin to grow. Budding pubic hair, growth of peach fuzz above the lips and armpit hair. The rapid shift from very low testosterone to normal adult levels causes behavioral changes.
After age 30: A gradual, inexorable decline of about 1 percent a year for the rest of a man's life.
The reality of 'low T'
It's unclear if heavily marketed testosterone replacement can stem age-related declines in muscle, sex drive or energy.
(Photodisc, Getty Images)