Obesity is associated with a significant number of health problems, including insulin resistance, cancer, and others, and now researchers may have uncovered a reason why. While most of your tissues and organs age at the same rate, certain factors may cause aging to accelerate.
For this reason, you may be “older” than your chronological age indicates, or certain organs may be more aged than others – a measure known as “epigenetic age.” One such factor linked to an acceleration of epigenetic aging is obesity, particularly in your liver.
Obesity Accelerates Aging in Your Liver
If you’re obese, new research found, your liver may be aging faster than the rest of your body, putting you at risk of chronic disease. For each increase in 10 body mass index (BMI) units, the epigenetic age of the liver grew by 3.3 years.
Steve Horvath, a professor of human genetics and biostatistics at the University of California, Los Angeles School of Public Health, explained:
“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… 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.”
Obesity surgery had no apparent effect on the age of the liver, even when it resulted in rapid weight loss. Further, obesity did not appear to impact aging in fat, muscle, or blood – only the liver.
Hovath and colleagues were able to measure the precise epigenetic age of liver samples using an “epigenetic clock” that Hovath developed. It’s based on DNA methylation—a process by which a methyl group (one carbon atom attached to three hydrogen atoms) is added to part of a DNA molecule.
DNA methylation is a crucial part of normal cell function, allowing cells to “remember who they are and where they have been” and is important in regulating gene expression.
DNA methylation also suppresses the genes for things you don’t want, such as viral and other disease-related genes, and abnormal DNA methylation plays a critical role in the development of nearly all types of cancer.
