Men Age Faster Than Women and Are "Four Years Older" by Time They're 50, New Study Reveals

Scientists say they've found evidence that men age faster than women, and men are biologically four years older than women by the time they're 50 years old. That's the conclusion of a new study which notes this "aging gap" also exists between men and women in their 20s. Read on to find out why. 

According to the study, published in The Journals of Gerontology, researchers in Finland looked at 2,240 twins in two age groups: Those between 21 and 42 years of age and those between 50 and 76. Using the epigenetic clock, a biochemical test used to measure age, the scientists compared each person's chronological age to how old the epigenetic clock said they are biologically. Four different epigenetic clocks were used to get the most accurate estimation of biological age. Researchers also assessed each participant's education level, BMI, and habits like smoking, drinking, and physical activity.

Epigenetic clock measures levels of methylation in a person's DNA. Methylation is a process in which certain molecules (called methyl groups) attach to the DNA in cells, damaging and aging them. It's been compared to barnacles attaching to the bottom of a boat and slowing it down.

Using the clocks, the researchers found that men were biologically older than women, and the difference increased with calendar age, even when accounting for lifestyle. "We found men are biologically older than women of the same chronological age, and the difference is considerably larger in older participants," said Anna Kankaanpaa, lead author of the study. "We observed a sex difference in aging pace, which was not explained by lifestyle-related factors."

The study author said that when comparing male-female twins, the male was about one year biologically older than his sister in his 20s and four years in his 50s. "These pairs have grown in the same environment and share half of their genes," said Kankaanpaa. "The difference may be explained, for example, by sex differences in genetic factors and the beneficial effects of the female sex hormone estrogen on health." Another potential factor: BMI, the researchers said. Men tend to be more overweight than women.

On average, women have outlived men since the invention of the actuarial table. But the gap in life expectancy is narrowing. In the 1970s, women outlived men by nearly a decade. Today, life expectancy in the U.S. is 81 years for women and 77 for men. One potential explanation, the Finnish scientists point out: Fewer men are smoking than in decades past.