Eat enough ultra-processed food and, on the inside, your body starts to look like it belongs to someone older.
That’s the consistent finding from several large studies measuring what researchers call biological age. In contrast to your chronological age, it’s the age your body most closely resembles, based on blood tests, organ function and other markers.
The differences are modest, but they show up in the US, the UK, Italy and Spain, across different populations and different measurement tools, and they may increase your risk of dying sooner. They add another line to what’s already a very long rap sheet for ultra-processed foods (UPF).
I’m quite good at avoiding ultra-processed food, apart from the Fruit ‘n’ Fibre I mix with my breakfast muesli, the supermarket chicken tikka masala rescued with brown rice and vegetables, and the packet biscuits (cookies, for readers across the Pond) I’m unable to resist. Perhaps one day I’ll retire and spend my afternoons baking them from scratch.
This is how ultra-processed food works its way into an otherwise sensible diet, through small negotiations with time, energy and convenience.
So, how concerned should we be that ultra-processed foods might make us age faster?
Biological age is an estimate, not a real clock running inside your body
So, what exactly is “biological age?”
There’s no hidden clock ticking away inside you that researchers can read off. Instead, biological-age tools take a collection of age-related signals and compare them against data from large numbers of volunteers. They then say, in effect, “Your results look like what we’d typically expect in someone who is x years old.” The output is usually the gap between that estimated age and your actual age.
Think of it like estimating someone’s age from their face. You look at wrinkles, age spots, skin texture and hair colour, and your brain makes a guess. Some of those features are genuinely caused by ageing, but others reflect sun exposure, smoking, alcohol or genetics. You’re estimating from a series of clues, and that estimate is only partly about how many years the person has been walking the earth.
Biological-age tools work the same way, just with blood tests or molecular data instead of crow’s feet.
There are three broad approaches:
Blood-based algorithms combine markers of inflammation, kidney function, blood sugar, immune activity and other systems into a single score.
DNA-methylation clocks measure chemical tags attached to DNA. The pattern of these tags changes with age, and can be compared against a reference dataset.
Telomere-length assays measure the protective caps at chromosome ends, which shorten as cells divide over a lifetime.
The more useful tools go beyond guessing chronological age. They’re designed to predict outcomes such as premature death, diabetes or declining organ function. There’s no single agreed standard, so different tools may give the same person somewhat different results.
So, a study can find that a group is “six months biologically older,” and that can help show the effects of a certain exposure, but it’s harder to interpret the results of a single individual. With that in mind, here’s what the studies show.
US reliance on ultra-processed food and its consequences
The study that illustrates the relationship most clearly comes from the US. Researchers analysed data from 16,055 adults in a large national health survey, using a blood-test-based algorithm called PhenoAge to estimate biological age.
The baseline figures show just how much UPF dominates the American diet. The average proportion of daily calories from ultra-processed food was 54%. Even the lowest-consuming fifth of participants still got about 30% of their energy from UPF, while the highest fifth averaged 77%. For many people in this study, ultra-processed food wasn’t a guilty pleasure; it was the majority of the diet.
The headline finding was that those eating the most UPF appeared 0.86 biological years older than those eating the least. The more UPF people ate, the bigger the effect: each additional 10% of energy from UPF was associated with 0.21 extra biological years. The association appeared stronger in adults aged 60 and over.
When researchers accounted for overall diet quality, that figure dropped to 0.14 years per 10%, suggesting that poorer nutrition explains part of the link, but not all of it.
To put that 0.21-year figure in perspective, earlier research has linked a PhenoAge gap of that size with an almost 2% higher risk of death over the following two years. That mortality figure comes from separate work, not from deaths observed in this study, but it gives a sense of the possible implications.
There are reasons to be cautious with our interpretation. Diet and biological age were measured at the same point in time, so we can’t establish which came first. Even the “lowest” group averaged about 30% of energy from UPF, so this wasn’t a comparison against a pristine, minimally processed diet. And 34% of participants had obesity, with rates climbing in step with UPF consumption.
Different populations and ageing tools point in the same direction
What strengthens these results is that several more studies, using different populations and different tools, have similar findings.
A second US analysis of 12,079 adults from the same national survey used a related but different algorithm. The highest consumers by weight appeared 0.6 biological years older than the lowest, and the researchers estimated that higher body weight accounted for about 28% of that difference.
Curiously, the relationship appeared when UPF was measured by weight but not by share of calories, which seems odd. The researchers suggested this might be because a larger physical quantity of UPF brings greater exposure to preservatives, sweeteners and other additives, regardless of calorie count. It’s an interesting idea, though at the moment it’s just speculation.
Across the Atlantic, UK Biobank provided the largest dataset, with 57,128 people, including both one-time measurements and data that followed participants over several years. The highest consumers appeared 0.38 years older in the snapshot and 0.53 years older when tracked over time. Body fat was estimated to account for 26–37% of the difference. The fact that the finding held up over time strengthens the case, though it doesn’t rule out other unmeasured differences between the groups.
The Italian Moli-sani Study again showed this link. Among 22,495 middle-aged and older adults, biological age was estimated from 36 blood markers. The highest consumers appeared 0.34 years older than the lowest.
The Italian participants consumed significantly less ultra-processed food. Average UPF intake was roughly 18% of energy, far below the 54% US average.
The relationship wasn’t a straight line: there was little difference below about 10–12% of energy from UPF, but the gap widened above that point. And when researchers accounted for Mediterranean diet quality, it explained just 9.1% of the difference, once again suggesting that something beyond nutritional content may be involved.
Taken together, four analyses involving more than 100,000 participants all point to differences of roughly 0.3–0.9 biological years between the highest and lowest UPF consumers. Despite differing tools, populations and proportions of UPF consumed the signal is remarkably consistent across the studies.
There’s also a piece of supporting evidence from a different ageing measure. In a Spanish study of almost 900 older adults, those eating more than 3 portions of UPF daily were 82% more likely to have short telomeres, the protective caps on chromosome ends that shorten as cells divide.
I find telomere data less compelling on its own, because telomere length is strongly influenced by genetics, early-life experiences and the type of tissue being measured. Still, it’s yet another finding pointing in the same direction.
While the findings are consistent, they don’t prove that UPF caused the ageing. These are observational studies, and there may be other differences between people who eat a lot of UPF and those who don’t that the researchers couldn’t fully account for. Still, it’s a striking and consistent signal.
If someone came to mind while you were reading this, please forward it to them. These tweaks may be small, but practised consistently they can genuinely change long-term health.
A useful nudge at the right moment can make all the difference.
Excess body fat explains part of the picture, but other factors are at play
Part of the explanation seems to be weight gain.
Ultra-processed foods tend to be energy-dense and low in fibre. They don’t fill us up, so it’s easy for us to overeat them. Across the studies, higher body weight consistently accounted for roughly a quarter to a third of the link between UPF and accelerated biological age: about 28% in one US analysis and 26–37% in the UK Biobank study.
But body fat and poor nutritional quality together don’t explain the whole picture. After taking these into account, the researchers found they only explained part of the effect. So what else might be going on?
Several plausible pathways have been proposed, though none has been confirmed as a direct contributor to the biological-age differences seen in these studies:
Disruption of the food’s natural structure in ways that may affect fullness and how the body processes nutrients.
Compounds generated by high-temperature industrial processing, including advanced glycation end products, acrylamide, furans and acrolein, which are linked to cell damage and inflammation.
Chemicals leached from plastic packaging, including phthalates and bisphenols.
Changes to gut bacteria and the intestinal lining that may increase inflammation.
Let’s not forget that ultra-processed food has been linked to much more beyond accelerated ageing.
For older adults, the these effects may be particularly relevant. An analysis combining results from 29 studies linked the highest UPF consumption with a 40% greater risk of frailty, with each additional 100g per day associated with a 3% higher risk.
And, in a catch-22, fatigue, chronic illness, dental problems and cognitive decline can make cooking from scratch harder, increasing reliance on convenient foods, which may in turn worsen the very conditions that led to them.
So, excess body fat is perhaps the single largest factor, and poorer nutritional quality adds to it when UPF displaces healthier foods. Beyond that, the mechanisms are plausible but unproven, and we can’t yet say which specific characteristics of ultra-processed food are responsible for the rest.
What this means for your health
Given the magnitude of ills now associated with ultra-processed food, I suspect accelerated biological ageing is a bit player. The more compelling reasons to cut back remain the links with premature death, cardiovascular disease, type 2 diabetes, obesity and frailty.
Still, the biological-age research does something useful in that it takes familiar effects on inflammation, blood sugar and organ function, and translates them into a concept that’s easy to grasp: Your body takes on the profile normally seen in someone a little older.
While that might sound insignificant, as we saw, previous studies have suggested that may be linked to around a 2+% higher risk of dying over the next couple of years. When you think of it that way, it no longer feels insignificant.
I’m not about to turf my Fruit ‘n’ Fibre and biscuits into the trash can - you’d have to prize the biscuits from my cold, dead hands! The bigger concern is what happens when ultra-processed food supplies the foundation of the diet.
And remember, roughly 57–58% of daily energy in the US and UK, and over 40% in much of Western Europe, already comes from ultra-processed foods. Italy does better at around 10–20%, and UPF consumption is growing in countries like South Africa (40%), Japan (30%) and Mexico (25–30%). [Source.]
So, while I don’t suggest we need to purge our kitchens of every single item of ultra-processed food, most evidence suggests that reducing how much you habitually eat might materially affect how long you live and how healthy you are.
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HEALTH TWEAK OF THE WEEK
Diets in which ultra-processed food dominates are consistently associated with modestly older biological-age profiles across US, UK, Italian and Spanish populations.
Separate studies suggest that such accelerated ageing is associated with an increased risk of dying over the next couple of years, and this just adds to UPF’s rap sheet, which already includes higher risk of premature death, cardiovascular disease, diabetes, obesity, mental health issues and perhaps even some cancers.
Cutting back on ultra-processed food is clearly wise, but the goal isn’t to eliminate every packaged food. It’s to reduce the proportion of your everyday diet supplied by ultra-processed products, starting with the one you eat most often or in the largest quantity.
1. Find your biggest repeat source. Look at 3 ordinary days and identify the packaged product you reach for most often or in the largest quantity: the breakfast cereal, the daily biscuits, the default ready meal, the go-to sugary drink. That’s your starting point.
2. Replace one default UPF at a time. Switch that single product for a less-processed option on most days:
Sweetened cereal or cereal mix → plain oats or muesli, with fruit, nuts and seeds.
Packet biscuits → fruit, yoghurt, nuts or wholegrain toast for some snacks.
Ready meals → keep them when you genuinely need them, but rotate with simple meals built around beans, lentils, fish, poultry, frozen vegetables or whole grains.
You don’t need to change everything at once. Make one replacement routine before choosing the next.
3. Keep convenience in its proper role. It’s fine to use ultra-processed food to bridge an occasional gap. The problem is when it quietly supplies most breakfasts, lunches, snacks and evening meals.
Add vegetables, legumes or whole grains to improve the overall meal, not because they cancel out the UPF on the plate.
Once the first swap feels routine, choose the next most frequent source.
The supermarket chicken tikka masala that saves me on the odd occasion when I’m running late and have nothing else to hand can stay. Maybe it’s the packet cereal I eat 300+ mornings a year that deserves another look.
🎧 Prefer to listen while sniffing out UPF in the kitchen cabinets?
🎙️ This week’s One Health Tweak a Week podcast looks at ultra-processed food and the emerging research on biological ageing.
You’ll hear:
What researchers actually mean when they say your body looks “biologically older”
Why several large US, UK and Italian studies have found broadly similar links between higher UPF intake and accelerated biological age
How much older the highest consumers appeared, and why differences measured in months rather than years can still be informative
How body fat and overall diet quality explain part of the association, with other possible mechanisms still uncertain
How to spot the ultra-processed foods that contribute most to your own diet, without turning every packet in the kitchen into a nutritional crime scene
👉 A good companion for your next walk, commute, or an exploratory rummage through the breakfast cupboard.
(Episodes are free for now. Paid subscribers support the deeper research behind them, along with the practical tools I’m developing to make that research useful in everyday life.)
🧭 Before you go
💬 Which ultra-processed food has become such a routine part of your diet that you barely think about it anymore?
Mine may well be the packet cereal I eat most mornings.
📤 Know someone whose kitchen contains a few similarly well-established regulars? Send this their way.
👥 Paid corner - If you’d like another pair of eyes on where ultra-processed food is contributing most to your own diet, drop me a note in our private chat. We can look at the foods you actually eat and work out which changes are likely to be worth the effort.
Until next Saturday, may your ready meals remain occasional, and your breakfast cupboard be filled with whole foods.
– Ben
This is such a complicated subject. Work stress, raising children while working full time, urban life, it all adds up to not having the time or energy to cook a decent meal. And what if both partners don't like to cook? I am writing about the younger generations here. My own children were raised on home cooked meals, but now? For all of the reasons above ................... Our modern culture has its priorities backward. Families are trying to survive, I don't think they have time to think about aging too fast.
Great article, Ben and totally unsurprising. I keep trying to tell my wife about the deadly consequences of UPFs.