Extra pounds cause the liver to age faster, potentially explaining why obesity is linked to diseases like liver cancer and insulin resistance, new research suggests. The study appears in the Proceedings of the National Academy of Sciences.

Steve Horvath, Ph.D., a professor of human genetics and biostatistics at the University of California, Los Angeles School of Public Health, and colleagues studied 1,190 samples of human tissue, including samples from more than 130 livers. They found that the epigenetic age of the liver grew by 3.3 years for each 10 body mass index units.

“Assume there is a man who is 5-foot-8 and weighs 130 pounds. This slender man would have a body mass index of 20,” Horvath told HealthDay. “Compare him to a man of the same age and height who weighs 230 pounds. The liver of this obese man — who has a BMI of 35 — would probably be five years older than that of the slender man.”

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The researchers found that weight-loss surgery didn’t have any effect on the age of the liver. However, they only looked at surgeries within the previous nine months, Horvath noted. The researchers don’t know how excess weight may affect the liver, but they found some clues.

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“We found a very strong adverse effect on liver tissue but we did not find any effect in fat, muscle, or blood,” Horvath said, adding that the next step for research is to understand if epigenetic aging rates will help doctors diagnose diseases in obese people or at least figure out which diseases they should be monitored for. “Ultimately, this line of research might lead to therapeutic interventions that not only keep the liver young but also the rest of the body,” he said.


  1. Horvath, Steve, et al. “Obesity accelerates epigenetic aging of human liver.” Proceedings of the National Academy of Sciences of the United States of America. doi: 10.1073/pnas.1412759111. September 15, 2014.