People whose everyday habits drifted toward smoking, poor diet, little exercise, heavy drinking or short sleep scored as aging faster on DNA-based tests, according to a study of Korean adults reported on October 30, 20261. The research, published in the journal Clinical Epigenetics, followed 1,020 middle-aged and older adults and looked at how changes in five habits over several years lined up with lab measures of biological aging and with an estimated risk of heart disease1.
The headline pattern was a gradient: compared with people whose habits stayed healthy, those whose habits got worse or stayed poor scored older, and the worse the trend, the bigger the gap1. Even people who improved their habits still scored somewhat older than the consistently healthy group within the 8-year window1.
What the researchers did
The participants came from the Korean Genome and Epidemiology Study, a long-running health study in Korea1. Their average age was 50.1 years, and 52.5% were men1.
The team built a lifestyle score from five habits people can change: alcohol, diet, physical activity, sleep and smoking1. Instead of taking one snapshot, they looked at each person’s direction over 4-year and 8-year stretches and sorted them into four groups: stable healthy, improved, worsened, or stable poor1. That design let them ask whether the direction of change over years, and not just someone’s habits at one moment, tracked with how fast their body appeared to age1.
They used two kinds of measures. The first was what scientists call epigenetic age acceleration: three “aging clocks” (named PhenoAA, Grim2AA and DunedinPACE) that read chemical tags on DNA, known as DNA methylation, and compare the pattern with a person’s calendar age to estimate whether the body is aging faster or slower than expected1. The second was an estimate of future heart and blood vessel disease risk, calculated with a standard formula called the PREVENT score1.
The numbers so far
On the Grim2AA clock, which is expressed in years, the gaps compared with the stable healthy group over the 8-year window were1:
- Improved habits: about 1.54 years older (range of likely values 0.81 to 2.27)1
- Worsened habits: about 2.45 years older (1.42 to 3.47)1
- Stable poor habits: about 3.81 years older (3.11 to 4.52)1
The DunedinPACE clock, which estimates the speed of aging, showed the same order. The difference was 2.20 for the improved group, 2.81 for the worsened group and 5.13 for the stable poor group, each compared with the stable healthy group1. The ranges around the DunedinPACE numbers were wide; for the worsened group, for example, the likely values ran from 0.25 to 5.371. The estimates were adjusted for other factors that could muddy the picture1.
The researchers also ran what is called a mediation analysis, which asks how much of a link between two things seems to pass through a third. In this case, faster scores on the aging clocks accounted for part of the link between habit changes and estimated future heart-disease risk: about 51.5% to 52.9% when measured with Grim2AA, and about 15.2% to 15.7% with DunedinPACE1. That means a share of the link ran through the aging-clock scores, but much of it did not, leaving other routes unexplained1.
The authors concluded that unfavorable changes in lifestyle were associated with poorer healthy-aging measures, and framed the results as pointing to the value of early and sustained healthy habits1.
What it does not show yet
This is an observational study. It watched people over time rather than asking some of them to change their habits, so it captures patterns, not proof that changing habits directly speeds up or slows down the DNA clocks1. People whose habits worsen may also differ in other ways, such as health problems, stress or income, and statistical adjustment can only account for factors that were measured.
Several other limits matter:
- Who was studied. The participants were a subset of a Korean study of middle-aged and older adults, and the findings may not apply to other populations1.
- Lab measures, not illness. The outcomes were scores on aging clocks and an estimated heart-disease risk from a formula, not heart attacks, strokes or deaths that actually happened1.
- Improvers did not fully catch up. The higher scores in the improved group hint that the effects of years of poor habits may not disappear quickly, at least within the time this study covered1. Whether a longer follow-up would show them closing the gap is an open question.
- Size of the study. At 1,020 people split into four groups, some estimates came with wide ranges of uncertainty, especially on DunedinPACE1.
Who is behind it
The study drew on the Korean Genome and Epidemiology Study and was published in Clinical Epigenetics, a peer-reviewed journal1. The coverage Biohack reviewed does not name the authors or say who funded the work, and no company or product is tied to the findings in that report. Biohack did not have access to the full paper.
How it fits the field
DNA-based aging clocks have become one of the main tools scientists use to track biological aging2. Much of the public attention has gone to small trials claiming habits can turn those clocks back. A 2021 pilot trial in 43 healthy men aged 50 to 72, for example, reported that an 8-week program of diet, sleep, exercise and relaxation guidance plus probiotics and plant-compound supplements was linked to a 3.23-year drop on one DNA clock compared with a group that got no program2. Its authors wrote that larger and longer trials were needed to confirm the result2.
The Korean study looks at the question from the other side and over a much longer stretch: not a short program, but what happens to clock scores when ordinary habits drift over 4 to 8 years1. Its results are in line with the idea that habits and aging clocks move together, but because no one was assigned to change anything, it cannot settle whether habits drive the clocks1.
Other Korean research has tied faster biological aging to physical decline. A separate study of 165,015 adults with an average age of 39.9, published in Geroscience in July 2026, found that faster aging measured from routine blood tests was linked to higher odds of losing muscle size and quality, and to a higher risk of developing those muscle problems over time3. That study used different aging measures, not DNA clocks, and also only shows associations3. Biohack has also covered other efforts to measure who is aging less healthily, including a 10-marker blood score.
What to watch next
- Longer follow-up. Whether people who improved their habits eventually match the consistently healthy group on aging clocks, which this study’s time window could not show1.
- Real health outcomes. Whether the clock differences seen here translate into actual heart attacks, strokes or other disease, rather than estimated risk scores.
- Other populations. Whether the same pattern shows up outside an East Asian group of middle-aged and older adults1.
- Trials that change habits on purpose. Larger and longer randomized trials, which the authors of the 2021 pilot said were needed, are the kind of study that could test cause and effect2.
This article reports research findings and is not medical advice.
