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Human bodies may be ageing faster than ever
Biological age is becoming higher than actual age.
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More and more serious research is being done on what is called biological age.
Biological age means that we can now measure how old our bodies are. You may be 45 years old. But your biological age may be 40 – or 50.
The message from some researchers is that people in a number of countries are now ageing faster than ever.
“Biological age is often a better measure of remaining lifespan or risk of age-related diseases than chronological age,” says Geir Selbæk, head of research at the Norwegian National Centre for Ageing and Health.
Diseases affect younger people
Annonse
Diseases that previously mainly affected older people – such as cancer, heart attacks, and type 2 diabetes – are now affecting people at a younger age than before, according to researchers at Yale University.
The researchers know why this is happening.
And they see that it is possible to slow this trend.
But first, a little about how researchers can measure biological age.
There are now many private companies that offer to tell you your biological age.
When serious researchers want to study biological age, it most often involves analysing chemical changes in our DNA.
These changes are popularly called epigenetic clocks.
These clocks are not entirely accurate, researcher Antonello Lorenzini warns in an interview with New Scientist. But they are good enough to see who is ageing faster or slower than others.
Obesity is the big culprit
For most of us, biological age and chronological age – that is, your age on paper – are more or less the same.
But quite a few of us have a biological age that is several years ahead or behind. Biological age can both increase and decrease, depending on our lifestyles.
Several research groups have now shown that much of the reason for this relates to obesity.
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A research group in Spain may have been the first to demonstrate this in 2016. Beatriz Gálvez and her colleagues saw that increased body mass index (BMI) and increased biological ageing have a clear tendency to follow each other.
Galvéz says that most of the people who experience premature ageing are adults with obesity.
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Both individuals with obesity and individuals with a high biological age are characterised by a dysfunction in white adipose tissue. This leads to metabolic syndrome, widespread inflammation, and possible damage to organs such as the kidneys, skeleton, heart, and blood vessels.
In 2017, a group of researchers affiliated with the University of Tampere in Finland found much the same in middle-aged individuals. They did this byy examining blood samples from 183 people taken 25 years apart.
In a very recent study from the University of Gothenburg, researchers who followed just over one million Swedish men over three decades found that high BMI and poor physical fitness in late adolescence are associated with serious bacterial infections later in life.
Obesity changes cells
Geir Selbæk explains that obesity leads to changes at the cellular level, which are called the 'hallmarks of ageing' – or characteristics of ageing.
“These can be changes such as increased low-grade inflammation, an increase in senescent cells (ageing cells/zombie cells, editor’s note), and impaired mitochondrial function. This strengthens the theory that obesity can have a direct effect on the ageing process,” Selbæk says.
But the relationship between obesity and increased biological ageing is probably explained by several factors, both direct and indirect, he adds.
A study in China
The problem for researchers in this field has been to determine whether obesity is the direct cause of increased biological ageing.
The studies have only shown a correlation, meaning that obesity and increased biological age are found to occur at the same time.
Now, however, a Chinese research group may have managed to show that one can actually lead to the other.
Using what is called Mendelian randomisation, this study provided strong evidence that obesity directly accelerates the body's biological ageing. Here, the researchers showed that faster ageing of the body's cells and organs can be linked to faster epigenetic clocks and telomeres that shorten more quickly.
At the same time, we cannot completely ignore the fact that both obesity and increased biological ageing share a common underlying cause.
One such common underlying cause could be that human bodies are exposed to an ever-increasing amount of calories.
Fasting can extend life
This is in line with studies showing that fasting promotes repair processes in the body and slows down ageing.
Perhaps this is because individuals who consume a lot of calories throughout the day never give their body the opportunity to initiate the necessary repair processes.
That means the body does not have time to repair the damage that leads to faster ageing.
A study in Chile
Chile is one place where there has been a significant increase in obesity and overweight in recent years.
Here, a group of researchers took a closer look at 205 individuals. These people have been followed from birth until they were almost 30 years old. The researchers have a great amount of data on them.
Researcher Paulina Correa-Burrows and her colleagues discovered some clear patterns:
- Those who had maintained a fairly normal weight from birth until they turned 30 had, on average, a biological age slightly below their chronological age.
- Those who had been obese since late adolescence were, on average, 4.2 years biologically older than they should have been.
- Those who had been obese since childhood were 4.7 years older biologically.
Some of the participants in the study had a biological age of over 40 when they were in their late 20s.
“We were expecting to find that, but we never expected the magnitude of difference that we saw in some individuals,” Correa-Burrows told New Scientist.
The obesity paradox
Geir Selbæk, head of research at the Norwegian National Centre for Ageing and Health, points out that the relationship between obesity or overweight and ageing and age-related diseases is complex.
“Obesity in midlife is associated with an increased risk of age-related conditions such as dementia or frailty,” he says. “But as people grow older, the relationship seems to reverse. That is, obesity appears to be somewhat protective, while low body weight increases risk. This is known as the obesity paradox.”
A possible explanation for this paradox is something called reverse causality. It may be that diseases or early stages of disease increase the risk of weight loss, rather than low weight causing disease.
Biological age is a better measure
Selbæk therefore believes that biological age is often a better measure of remaining lifespan or risk of age-related diseases than chronological age.
“Biological age can be calculated in many ways,” he says.
The most common approach has been to create a composite score for a number of physical functions or biological measurements related to the function of organs and the body.
“In recent years, epigenetic analyses, most often measures of DNA methylation, have gained increasing popularity, both in research and for individuals. At the individual level, the validity of these measures is uncertain, but at the group level they can probably provide important information,” he says.
A society that promotes obesity
Researchers who specialise in overweight and obesity sometimes talk about living in an ‘obesogenic environment.’
We live in a society that promotes obesity.
We move through environments where we have almost unlimited access to calorie-dense, inexpensive food that tastes good.
This also relates to physical activity, which has become something many people don’t get enough of in their everyday lives. Physical activity has become something we need to actively seek out. Being physically active is consequently reserved for people with enough resources and drive to get off the couch.
This essentially creates a class-based society linked to the body.
Stress that affects the body
Some research also points to the fact that stress and trauma from violence, poverty, or insecurity can affect the body and accelerate ageing.
Some studies have shown that socially isolated people may age faster.
At the same time, obesity among children and adolescents has exploded globally.
People who are overweight as children often remain overweight or develop obesity as adults. This means that many risk entering adulthood with 'extra ageing' already present in their bodies.
References:
Lawton, G. Our bodies are ageing faster than ever. Can we hit the brakes?, New Scientist, 2025.
Li et al. Causal association of obesity with epigenetic aging and telomere length: a bidirectional mendelian randomization study, Lipids in Health and Disease, 2024. DOI: 10.1186/s12944-024-02042-y
Pérez et al. 'Adipaging': ageing and obesity share biological hallmarks related to a dysfunctional adipose tissue, Journal of Physiology, 2016. DOI: 10.1113/JP271691
Sourander et al. High BMI and low cardiorespiratory fitness in adolescence are associated with increased risk of severe bacterial infections in adulthood, Journal of Internal Medicine, vol. 299, 2025. DOI: 10.1111/joim.70043
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Translated by Nancy Bazilchuk
Read the Norwegian version of this article on forskning.no
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