12 surprising signs you’ll live to 100

You're the life of the party
Outgoing people are 50 percent less likely to develop dementia, according to a recent study of more than 500 men and women age 78 and older from the Karolinska Institutet in Sweden. Participants also described themselves as not easily stressed.

You run for 40 minutes a day
Scientists in California found that middle-aged people who did just that — for a total of about 5 hours per week — lived longer and functioned better physically and cognitively as they got older; the researchers tracked runners and nonrunners for 21 years.

You like raspberries in your oatmeal
Most Americans eat 14 to 17 g of fiber per day; add just 10 g and reduce your risk of dying from heart disease by 17 percent, according to a Netherlands study. Dietary fiber helps reduce total and LDL ("bad") cholesterol, improve insulin sensitivity, and boost weight loss. One easy fix: Top your oatmeal (½ cup dry has 4 g fiber) with 1 cup of raspberries (8 g) and you get 12 g of fiber in just one meal.

You feel 13 years younger than you are
That's what older people in good health said in a recent survey of more than 500 men and women age 70 and older. Feeling youthful is linked to better health and a longer life. It can improve optimism and motivation to overcome challenges, which helps reduce stress and boost your immune system and ultimately lowers your risk of disease."

You embrace techie trends
Learn to Twitter or Skype to help keep brain cells young and healthy. Many of the oldest Americans send e-mails, Google lost friends, and even date online. Researchers say using the latest technology helps keep us not only mentally spry but socially engaged: Stay connected to friends, family, and current events, and you feel vital and relevant.

You started menopause after age 52
Studies show that naturally experiencing it later can mean an increased life span. One reason: Women who go through menopause late have a much lower risk of heart disease.

You make every calorie count
Researchers in St. Louis reported that men and women who limited their daily calories to 1,400 to 2,000 (about 25 percent fewer calories than those who followed a typical 2,000-to 3,000-calorie Western diet) were literally young at heart — their hearts functioned like those of people 15 years younger. It's about not just eating less but getting the most nutrition per calorie. Study subjects stuck to vegetables, whole grains, fat-free milk, and lean meat and nixed white bread, soda, and candy. If you cut empty calories and eat more nutrient-rich foods, your health will improve. To find out how many calories you need to maintain a healthy weight, go to prevention.com/caloriecalculator.

You had a baby later in life
If you got pregnant naturally after age 44, you're about 15 percent less likely to die during any year after age 50 than your friends who had their babies before age 40, reports a recent University of Utah study.

Your pulse beats 15 times in 15 seconds
That equates to 60 beats per minute — or how many times a healthy heart beats at rest. Most people have resting rates between 60 and 100 bpm, though the closer to the lower end of the spectrum, the healthier. A slower pulse means your heart doesn't have to work as hard and could last longer.

You don't snore
Snoring is a major sign of obstructive sleep apnea, a disorder that causes you to stop breathing briefly because throat tissue collapses and blocks your airway. Sleep apnea can cause high blood pressure, memory problems, weight gain, and depression. An 18-year study found that people without OSA were 3 times more likely to live longer than those with severe apnea. If you snore and have excessive daytime drowsiness or mood changes, talk with your doctor about a referral to a sleep center.

You have a (relatively) flat belly after menopause
Women who are too round in the middle are 20 percent more likely to die sooner (even if their body mass index is normal), according to a National Institute on Aging study. At midlife, it takes more effort to keep waists trim because shifting hormones cause most extra weight to settle in the middle.

You get your blood tested for vitamin D levels
For optimal disease protection, we need at least 30 nanograms of vitamin D per milliliter of blood, reports a study in the Archives of Internal Medicine. Nearly 80 percent of Americans have less than that. Vitamin D not only helps bones ward off osteoporosis but may also reduce your risk of cancer, heart disease, and infection. If needed, you can take a daily supplement to get your numbers up. Doctors can measure your levels with a simple blood test, but periodic monitoring may be necessary — vitamin D turns toxic at 100 to 150 ng/mL.