IJO: Higher Body Weight in Adolescence Linked to Faster Biological Aging

A higher body mass index (BMI) during adolescence is associated with faster biological aging decades later, according to Finnish researchers who analyzed data from a long-term study that began in 1980. The findings were published in the International Journal of Obesity (IJO).

The researchers examined data from 2,045 participants in the Cardiovascular Risk in Young Finns Study. They compared BMI measurements — the ratio of weight to height — collected from childhood through adulthood with epigenetic markers of aging that can be used to estimate biological age and the rate at which the body ages.

The study found that a higher BMI during adolescence was more consistently associated with accelerated biological aging than the rate at which BMI increased during those years, or weight gain itself. The strongest association was observed among people who had both a high BMI and a genetic predisposition to higher body weight.

To assess biological aging, the researchers used several epigenetic clocks based on DNA methylation patterns. The most compelling results were obtained with DunedinPACE, which estimates the rate of biological aging.

The researchers also used Mendelian randomization to investigate whether a high BMI might have a causal effect on accelerated aging. One of the genetic analyses supported this possibility. However, after accounting for BMI in adulthood, the association became substantially weaker and was no longer statistically clear.

The authors emphasize that BMI is only an indirect measure and cannot distinguish between fat mass and muscle mass. In addition, the study participants were predominantly of European ancestry and from Finland, so the findings cannot automatically be generalized to other populations.

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