"I think it's all about maintaining a positive outlook on life and approaching each day with a can-do attitude," says Spiliotes, when asked how she has managed to remain healthy and fracture-free. She was diagnosed with the condition 13 years ago after complaining to her doctor of aches and stiffness.

For millions of other men and women, Osteoporosis is a diagnosis they receive only after some minor bump or slip sends them to the emergency room with a fractured hip, wrist or back. Nicknamed "the silent disease," Osteoporosis causes bones to weaken and deteriorate secretly, without any obvious signs.

"Bone continually breaks down and builds itself up throughout your life; but, once you reach your 30s, your bones do not build up as much as they break down," says Dr. Jeanette Magnus, clinical professor of public health at the Tulane University School of Public Health and Tropical Medicine.

When bones begin breaking down more than they build up, they become more porous and less dense, thus the word "osteoporosis" which means "porous bones." The stronger your bones are before you reach your 30s, the more stored up bone mass you will have to work with later.

"It is like placing money in the bank -- your bone bank!" Dr. Magnus explains. "You start to pull out the interest -- the bone mineral content -- after you are 30 years old, and live on that for the rest of your life."

Women are more at risk of developing Osteoporosis than men are. According to the National Institutes of Health, one out of every two women older than 50 will have an Osteoporosis-related fracture in their lifetime, as opposed to one in eight men.

Post-menopausal women are more at risk than pre-menopausal women. According to the National Osteoporosis Foundation, women can lose up to 20 percent of their bone mass in the first five to seven years after the onset of menopause.

Other risk factors include:

• Thin and/or small frame
• Advanced age
• A family history of Osteoporosis
• Early menopause
• A diet low in calcium and vitamin D
• Use of certain medications, such as corticosteroids and anticonvulsants
• Low testosterone levels in men
• An inactive lifestyle
• Cigarette smoking
• Excessive use of alcohol
• Caucasian or Asian, although African Americans and Hispanic Americans are at significant risk as well

Bones crave calcium. Our bones hoard 99 percent of the calcium in our bodies, allowing only a scant one percent to be used by our blood.

Dr. Magnus encourages parents to start thinking of their children's bone health now by stressing physical exercise and nutritious, calcium-rich foods. Studies show that most people consume less than half the amount of calcium they need. According to Dietary Reference Intake Guidelines from the Institute of Medicine, children ages 9 to 18 need 1,300 milligrams of calcium a day. Nineteen to 50-year-olds require 1,000 milligrams daily and after that it's back up to 1,200 milligrams a day for the duration of life.

Calcium is available from the top to the bottom of the food pyramid. Good sources of calcium include low-fat dairy products, such as milk, yogurt, cheese and ice cream; dark green, leafy vegetables, such as broccoli, collard greens, bok choy and spinach; sardines and salmon with bones; tofu; almonds; and foods fortified with calcium, such as orange juice, cereals and breads. Depending upon how much calcium you get each day from food, you may need to take a calcium supplement.

To learn how much calcium is in a food, you can read the food label's Nutrition Facts panel. Look for the "Percent Daily Value" (%DV) set by FDA for calcium. The calcium DV is 1,000 milligrams. If you are in an age group requiring more than 1,000 milligrams a day, you should adjust your figures accordingly. For example, if you are older than 50 and need 1,200 milligrams a day, each day's calcium percent Daily Value in the foods you eat should add up to 120 percent.

To identify foods with at least 10 percent of the Daily Value of calcium per serving, the FDA allows these terms on their labels:

• 20 percent DV or more: "High in Calcium," "Rich in Calcium," "Excellent Source of Calcium"
• 10 to 19 percent DV: "Contains Calcium," "Provides Calcium," "Good Source of Calcium"
• 10 percent DV calcium or more added: "Calcium-Enriched," "Calcium-Fortified," "More Calcium."

Vitamin D is calcium's indispensable sidekick. Bone needs vitamin D to move calcium from the intestine to the bloodstream and into bone. Because the only sources of vitamin D are normal day-to-day exposure to sun and from foods like milk, which are fortified with the vitamin, you may need a supplement to get the 400 to 800 International Units needed each day. Studies show that vitamin D production decreases in the elderly, in people who are housebound, and during the winter when the sun is not as strong.

Like muscle, bone is living tissue that responds to exercise by becoming stronger. Mona Calvo Ph.D., a calcium expert for the Food and Drug Administration, says impact activity, such as jumping up and down, appears to be the best workout for bones. Other activities which force you to work against gravity include climbing stairs, jumping rope, dancing, hiking, football and gymnastics. While swimming and cycling are excellent aerobic exercises, they tend to put less pressure on the bones and therefore do less to increase skeletal mass.

"But the important thing is to get off the couch and get moving at some activity," says Calvo. "It really is a matter of 'Use it now, or lose it later.'

"Cigarette smoke is also toxic to bone and can influence how much exercise you get because it affects your stamina," adds Calvo.

Are There Any Medications for Osteoporosis?
Studies have shown that post-menopausal women on hormone replacement therapy (HRT) show an increase in bone mass. Certain drugs can also reduce your risk of fractures, including Fosamax and Miacalcin Nasal Spray, which reduce bone loss, and Evista, a new drug that can prevent bone loss.

How Do You Know If You Have Osteoporosis?
A bone density tests is a quick, painless and non-invasive procedure. In most cases, you don't even need to undress. Tests can take anywhere from 30 seconds to 5 minutes and require no special preparation, medication or injection. If diagnosed with Osteoporosis or low bone mass, the sooner you know about it the sooner you can start taking steps to treat it, and the better off you will be.

Just ask Lia Spiliotes. "Naturally I worry about mobility issues, about being able to keep up with a young son in the future," she says. But so far, thanks to balanced meals, calcium supplements and her winning positive attitude, she has not missed a beat.

"These are the great years," she says. "I want to enjoy them."