Researchers Tracked Children for 40 Years, Then Found a Clue About Aging - Newsweek

Having a higher body mass index (BMI) in adolescence may have repercussions well into adult life, according to the findings of a new study.

Researchers at the University of Jyväskylä, Finland, found an association between higher teenage BMI—the measure of body weight relative to height which is used to screen whether someone is underweight, overweight or obese—and faster biological aging. The study was published in the International Journal of Obesity on August 12.

Elina Sillanpää, study lead and associate professor in health promotion at the University of Jyväskylä, Finland, told Newsweek that accelerated biological aging "predicts a greater risk of functional limitations, cardiometabolic diseases, cognitive decline, and earlier death."

"This suggests that exposures and behaviors earlier in life can leave biological marks that influence how rapidly we age and how many healthy years we are likely to have in the future," she said.

The researchers reviewed the biological data of more than 3,500 participants from the Young Finns Study, who were followed from 1980 through to between 2018 and 2020.

They said that adolescents with a genetic susceptibility to higher BMI, as well as those with elevated BMI not influenced by genetics, might be prone to obesity-related health risks in adulthood.

The researchers said the findings highlighted the need for early prevention strategies.

Dr. Thomas Robinson, a professor in child health and director of the Center for Healthy Weight at Stanford University, told Newsweek he was not surprised by the findings as "it has been known that obesity is associated with various measures of advanced biological aging, including among children with obesity."

He pointed to a 2023 study he was involved in that he said found "a reversal of biological aging in children with obesity during their participation in a six-month behavioral weight control program."

He said the results "suggested taking action by participating in a program promoting higher quality, low calorie, low fat, low sugar eating, more physical activity, and less screen time, significantly slowed the children's rate of biological aging."

Sillanpää said that a higher BMI in adolescence "may accelerate biological aging because excess adiposity is associated with chronic low-grade inflammation and metabolic disturbances that can promote cellular aging." Adiposity refers to the prevalence of fatty tissue in the body.

As fat cells in the body grow larger, those cells release hormones and other chemicals that cause inflammation, which spread around the body. That inflammation can then interfere with how the body uses insulin, resulting in metabolic issues.

That systemic inflammation over time can lead to age-related diseases appearing earlier like heart disease, certain types of cancer and neurodegenerative diseases, according to the National Council on Aging.

Sillanpää added that it was therefore "particularly concerning" that the effects of a higher BMI "may not become fully apparent until decades later."

She also said that higher BMI may "act as a marker of other unfavorable lifestyle exposures, such as low physical activity and poor diet, which may further contribute to accelerated aging processes."

Sillanpää said, based on the findings, it is important that people "invest in societal and environmental changes that help prevent weight gain before it occurs."

"Rather than placing the burden entirely on individuals, we should create healthier schools, neighborhoods, and food environments that support healthy lifestyles from childhood onward," she said. "Early prevention is likely to yield substantial benefits not only for obesity prevention but also for reducing future risks of chronic disease, functional decline, and premature mortality."

Robinson said that more studies now need to be done to "measure benefits of different treatments for children with obesity and try to delay, reduce or prevent adult chronic diseases by promoting a healthy weight and healthful eating, activity and screen time behaviors in children."

Pitkänen, A., Kankaanpää, A., Raitoharju, E. et al. (2026) Adolescent weight gain trajectories and their associations with biological aging: a genetically informed study. International Journal of Obesity. https://doi.org/10.1038/s41366-026-02194-0