But if you exercise pretty frequently and eat right, you might be a lot younger than you think - at least as far as something called your "fitness age" is concerned.
The "fitness age calculator," which determines your fitness age based on how physically fit you are (rather than how many years you've been around), was developed in 2013 by researchers at the Norwegian University of Science and Technology. Most recently, researchers tried out the calculator on athletes competing in the National Senior Games, a massive annual event with over 12,000 athletes ages 50 and over competing from July 3-16.
While the average chronological age of the participants was 68, their average fitness age was a striking 43, the New York Times reported recently.
The calculator works by taking information about where you live, your age and gender, how frequently you exercise, your heart rate, and your height and waistline measurements.
Then, using these variables, the calculator comes up with something called your VO2max, a measure of how much oxygen your body can take in, measured in milliliters of O2 per kilogram of body weight per minute. While your VO2max is influenced by your age and gender, it's largely determined by your workout regimen - generally speaking, the more you exercise, the more oxygen your body can absorb.
What can your fitness age tell you about your health?
We spoke with Dr. Amy Ehrlich, a geriatrician at the Albert Einstein College of Medicine, see what her thoughts on the calculator were. She told Business Insider that she found the fitness calculator compelling.
At its core, the calculator shows that as long as a person is not overweight and exercises regularly, the chances of getting sick and dying at an earlier age lessen, Ehrlich said.
According to a recent Gallup survey, about 70% of people the US are either overweight or obese, so most Americans who try out the calculator would probably get a fitness age that's higher than their actual age.
In people older than 65, regular exercise has been found to help stave off a host of diseases, including colon cancer and depression. And it's never too late to start, says Ehrlich. People who begin exercising as late as 85 can drastically improve their health, she said. Of course, you should consult with a health professional about what types of exercise to engage in to be sure you don't overdo it.
We gave it a try - and got some good news
I tested it out: I'm a 22-year-old woman living in New York City, and I exercise for at least 30 minutes about two-to-three times each week. After popping this info into the calculator, as well as some educated guesses about my waistline and resting pulse, it told me I had the fitness age of a 20-year-old. Oh, to be a sophomore in college again!
To see how weight gain could impact my fitness age, I increased my weight by 70 pounds and upped my waistline size by 10 inches. Surprisingly, my fitness age changed to 36.
See how your fitness age compares to your real age: