September 24, 2026, 4:38 pm | Read time: 3 minutes
Overweight in youth is considered a risk factor for numerous diseases. A new long-term study from Finland now suggests that the consequences could be even more far-reaching: Teenagers with a higher BMI showed signs of accelerated biological aging decades later. Those particularly affected were individuals genetically predisposed to higher body weight.
For the study, researchers used data from the so-called Young Finns Study.1 This study has followed the same participants from childhood into middle adulthood since 1980. Data from more than 2,000 individuals, whose BMI was recorded at ages 9, 12, 15, and 18, were evaluated. Additionally, the scientists examined blood samples from various life stages. Using so-called epigenetic clocks, they analyzed chemical changes in DNA that provide clues about how quickly the body ages biologically. The researchers also calculated genetic risk scores indicating how strongly a person is genetically inclined to a higher BMI.
Higher BMI in Youth, Faster Aging Later
The analysis showed that individuals with a genetic predisposition for a higher BMI aged biologically faster than those with a lower genetic risk. This connection was still evident in their 40s and 50s.
Particularly interesting: It was not the speed of weight gain during youth that seemed decisive. Rather, the weight at the beginning of the teenage years played a more significant role. Those who already had a higher BMI early on showed stronger signs of accelerated aging processes later.
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Evidence of a Causal Connection
To determine whether overweight actually contributes to faster aging or if there is merely a statistical correlation, the researchers used a method called Mendelian randomization. It was found that a genetically higher BMI in youth is likely directly linked to faster biological aging. However, the results varied depending on the genetic model and aging marker used.
What Do the Results Mean?
The connection is largely explained by the fact that high weight in youth mostly persists into adulthood. However, adults who reduce or maintain their weight may be able to counteract accelerated aging. Additionally, the study focused exclusively on individuals of European descent.
The researchers also emphasize that biological aging is only a marker and does not automatically mean that those affected will become ill or die earlier. Nevertheless, accelerated biological aging is considered an indicator of an increased risk for various chronic diseases later in life.
The study thus provides further arguments for taking overweight seriously in childhood and adolescence. The effects could accompany the body much longer than previously assumed.