This fascinating 2014 human study developed the new use of a somewhat intuitive marker of aging. The researchers used the degree of methylation – an epigenetic chemical modification of DNA – as an epigenetic clock to measure biological age.

The researchers found that, on average, the epigenetic age of the liver increased by 3.3 years for every increase in 10 body mass index (BMI) units. Other studied tissue areas weren’t similarly affected.

http://www.pnas.org/content/111/43/15538.full “Obesity accelerates epigenetic aging of human liver”