There is increasing interest in the science of aging and how we can use that knowledge to reverse the clock. And start-ups like Tally Health are promising to provide that insight into how we age and, potentially, how to get ahead of it.

Tally Health created and administers a test that collects DNA samples from a cheek swab, and calculates what the company calls a "biological age." The process involves identifying how your body ages on a cellular level based on epigenetics.

"We call it the credit score for the body that measures all aspects of your health," Dr. David Sinclair, a Harvard scientist and longevity expert, tells CNBC Make It.

Sinclair co-founded Tally Health and, as its scientific advisor, had a hand in creating its test which partly relies on his years of research in the field of longevity.

"We have a new understanding of why we age, and how important it is to live a lifestyle that slows down that process. Because we're aging every day," he adds.

I was offered the opportunity to take the "TallyAge Test" and despite my generally healthy lifestyle, I was still a bit nervous to learn my biological age.

Here are my results, and how I was advised to interpret them.

My 'biological age' is just one month older than my actual age

Though the goal is to have a younger biological age than your actual age, only a drastically older biological age may be cause for concern, says Adiv Johnson, the director of research and innovation at Tally Health.

According to my results, my "TallyAge" is around 23 years and 7 months, just one month older than I was when I took the test in January.

And having the same biological age as your actual age is pretty great, says Johnson. But, "if I was 85, and I got told that it looks like a typical 95-year-old's [DNA], there I might feel differently or respond differently," he adds.

And as it turns out, my eating habits may be responsible for my positive results. I eat a mostly plant-based diet.

"What we found with our model is, on average, people that exercise tend to [test] younger than people that don't exercise. People that eat lots of plant-based foods correlate with a younger TallyAge," Johnson says.

The same correlation is seen for people who get enough good-quality sleep, are more socially fulfilled and drink less alcohol, he adds.

"There's of course variability, because human beings are so complex," Johnson says. Some people who smoke cigarettes often, have gotten younger biological ages, which he believes is likely due to their genetics.

'More than 90% of how you age is up to lifestyle choices, environment'

While my biological age is pretty low, I was advised to strive for an even lower one to help reverse some of my aging.

"You can naturally lower your TallyAge by adopting the right lifestyle habits. More than 90% of how you age is up to your lifestyle choices and environment," Tally Health advised in my results.

TallyAge test results come with a questionnaire about your behaviors like what you eat, how often you exercise and more. Using your responses, the company creates an action plan to improve your lifestyle, and hopefully reduce your biological age.

The company aims to help you track if, and how, your behaviors are affecting how you're actually aging.

Users are encouraged to track their progress over time by taking a Tally test, and completing the lifestyle questionnaire, quarterly.

A Tally Health test will cost you $229, but the company also offers monthly and yearly subscriptions with prices that vary.

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