Table 2.

DNAm clock and pace-of-aging measures included in CALERIE analysis

DNAm clocks. DNAm clock measures of aging are algorithms that estimate biological age, the state of an organism’s biology represented as the age at which that state would be typical in a reference population. The clocks we analyzed were developed to predict mortality risk. The age values computed by the clock algorithms correspond to the age at which predicted mortality risk would be approximately normal in the reference population used to develop the clock. We computed clock values based on versions of the clock algorithms developed from DNAm PCs (sometimes referred to as ‘PC clocks’)18,21.
PhenoAge clock	Based on analysis of nine blood chemistry markers, age and mortality data from the US National Health and Nutrition Examination Surveys (n = 9,926 participants aged 18 yr and older; 23 yr of mortality follow-up); DNAm and blood chemistry data from the InCHIANTI Study (n = 912 participants aged 21–100 yr); and the US Health and Retirement Study (n = 3,593 participants aged 51–100 yr)19.
GrimAge clock	Based on analysis of eight plasma protein markers, smoking pack years, age, sex and mortality data from the Framingham Heart Study Offspring Cohort (n = 2,356 participants aged 24–92 yr)47–49.
Pace of aging. Pace-of-aging measures estimate the rate of biological aging, defined as the rate of decline in overall system integrity. Pace-of-aging values correspond to the years of biological aging experienced during a single calendar year. A value of 1 represents the typical pace of aging in a reference population; values above 1 indicate faster pace of aging; values below 1 indicate slower pace of aging.
DunedinPACE	Based on analysis of pace of aging in the Dunedin Study (n = 817 participants examined at ages 26, 32, 38 and 45 yr)24. Pace of aging was measured from within-person change over time in 19 blood chemistry and organ function test metrics of system integrity24. DNAm was measured at age 45 yr.