Granola bars, despite their healthy image, can accelerate ageing. That is the warning from GP Asiya Maula, a functional medicine specialist at The Health Suite in Leicester, who says that even snacks labelled as “natural” can trigger the kind of metabolic stress that speeds up the body’s biological clock.
Surprising food culprits that drive premature ageing
The problem, Dr Maula explains, is not always the obvious junk food. Three everyday items that many people reach for as “healthy” options are among the worst offenders: granola bars, fruit juice and low-fat yoghurt.
Granola bars, even those marketed as natural, often contain honey, syrups and dried fruit. These ingredients can cause sharp spikes in blood sugar. “Frequent blood sugar spikes can contribute to inflammation and energy crashes over time,” Dr Maula notes. “This can impact metabolic health, which is closely linked to how the body ages.”
Fruit juice is another hidden danger. Without the fibre structure that is present in whole fruit, the body processes juice very differently. “When sugars are absorbed quickly, it can lead to fluctuations in blood sugar and increased hunger later on,” she says. “Over time, this pattern may contribute to processes associated with ageing.”
Low-fat yoghurt, often chosen for its lower calorie count, is the third culprit. Dr Maula explains: “Removing fat often leads to products being reformulated with extra sugar or additives. That can affect satiety and metabolic balance in ways people don’t expect.”
The science of blood sugar spikes and faster ageing
To understand why these foods are problematic, it helps to look at what happens inside the body after a blood sugar spike. The process is rooted in what researchers call “inflammaging” — a term that combines inflammation and ageing. This chronic, low-grade inflammation damages cells, impairs tissue repair and accelerates visible signs of ageing.
High blood sugar levels trigger a chemical reaction known as glycation, in which sugar molecules bind to collagen and elastin — the proteins that keep skin firm and elastic. This damages them, making skin weaker, thinner and less elastic, contributing to fine lines, sagging and dullness. The result is a build-up of Advanced Glycation End Products (AGEs), which accumulate in tissues and accelerate cellular ageing.
The same metabolic stress also drives broader health problems. Research from the University of Birmingham’s Department of Inflammation and Ageing focuses on how inflammatory processes drive human ageing and on interventions to prevent age-related diseases. The links are clear: chronic inflammation and metabolic stress are key drivers of premature ageing, and diet plays a central role.
Ultra-processed foods — which, like many commercial granola bars and low-fat yoghurts, are often high in sugar, unhealthy fats and additives — have been shown in studies to accelerate biological ageing. Data indicates that for every 10% increase in energy intake from ultra-processed foods, biological age can increase by 0.21 years. In the UK, such products account for more than half of calorie intake in some populations.
Dr Maula’s concerns are backed by nutritional audits. A UK study found that 37% of “healthy” snack bars were high in sugar, and 55% were high in saturated fat. Some bars contain up to seven teaspoons of sugar per serving. Similarly, a survey of UK supermarkets found that 55% of low-fat yoghurts still contain between 10 and 20 grams of sugar per 100 grams.
Fruit juice, though it retains some of the natural fruit matrix, remains a concentrated source of free sugars. The UK government recommends that free sugars — including those in fruit juice — should not exceed 5% of daily energy intake. High consumption of fruit juice has been linked to an increased risk of type 2 diabetes.
Practical swaps for healthier ageing
Dr Maula emphasises that small, repeated dietary choices have a significant impact over time. “It’s not about cutting foods out completely but making smarter swaps that better support the body,” she says.
For a stable energy source, she recommends replacing granola bars with plain oats, eggs, or natural yoghurt with fresh fruit. Whole fruits should be eaten rather than drunk as juice; if juice is consumed, limiting intake to 150ml per day and pairing it with a meal can help slow sugar absorption. Smoothies made with whole fruit, water and vegetables are a better alternative.
When it comes to yoghurt, Dr Maula advises choosing full-fat or natural varieties. These support more stable energy levels and keep the body fuller for longer, avoiding the hidden sugars that often accompany low-fat reformulations.
The broader picture, says Dr Maula, is about improving “healthspan” — the number of years lived in good health — rather than solely focusing on lifespan. Regular exercise can significantly reduce harmful inflammation and improve metabolic profiles, with improvements seen in 19 out of 20 markers linked to metabolism and inflammation. Managing chronic stress through techniques such as breathwork and ensuring adequate sleep are also crucial, since stress can amplify oxidative stress and lead to persistent inflammation.
Dr Maula holds Master’s distinctions in Public Health and Medical Education, certifications from the Institute of Functional Medicine (USA) and the International Board of Lifestyle Medicine, and is a Metabolic Terrain practitioner. Her approach integrates conventional medicine with functional and lifestyle principles, addressing root causes rather than just symptoms.
“People often assume that if a food is considered healthy, it will automatically support longevity,” Dr Maula said. “But how your body responds to that food on a basic level is what really matters when it comes to ageing well.”