When it comes to hot flashes and hormones, most people think of women going through menopause. But men can go through something similar. It's called andropause, or male menopause, and it can play a significant role in a man's life.

For Dr. Bob Hood, 57, it began when he noticed some changes: "Increased fatigue at the end of day -- the end of week, particularly -- increased body fat, probably decreased libido," Dr. Hood recalled.

He assumed it was just part of getting older, but his doctor told him his hormone levels were low due to andropause.

When 53-year-old Richard Casey's doctor told him the same thing, he was shocked.

"Everybody's heard about menopause," Casey said. "It's sort of like hormones were a woman thing, you know. Guys don't think about that."

According to Dr. Richard Giannotto, the founder of the Longevity Center, male menopause is "due to a decrease in certain hormones in a man, specifically testosterone, secondarily, growth hormone and something called DHEA." Unlike menopause, the hormonal change with andropause is gradual. Doctors say all men go through it, some starting in their 40s. And although many men are unaware it's happening, or even exists, sometimes their spouses are more in tune.

"A lot of men have wives, you know, feeling so much better on their hormone replacement therapy, and they start thinking, 'I wonder if my husband would feel better,'" said Dr. Alicia Stanton, the chief medical officer for BodyLogicMD.

Low hormone levels make it harder to lose weight in the mid-section, and can cause problems with short-term memory and focus.

Other symptoms include a loss of libido, irritability and depression, which can affect relationships, particularly if a partner is also coping with hormonal changes.

"If both parties are not focusing and depressed, and not communicating well, their relationship can really run into a snag," Dr. Stanton said.

Both Hood and Casey started hormone replacement therapy, improved their diets and exercise regimes, and have seen noticeable improvements.

"My memory has improved, my sex drive is back, you know, so my wife can enjoy better marital relations," Casey said.

"I feel great," added Dr. Hood. "I feel better, markedly better."

Doctors say a three-part approach is the key: improve diet, increase exercise, and, if needed, use hormone replacement therapy.

They say when done correctly, the male menopause patient will feel significantly better, and will reduce his risk for heart disease, stroke, diabetes and osteoporosis.