The Simpson Prize 2025 | Highly Commended - Caitlin Andrews

I’ve always been partial to a good health metric. Resting heart rate? Love it. Sleep score? Addicted. I once tracked my blood glucose for a week just to see what happened after a cinnamon scroll. (Spoiler: my pancreas sent a cease-and-desist and ghosted me entirely.)

So, when I stumbled across a study claiming that a six-week dietary intervention could improve how fast your body is aging, I did what any health-curious journalist would do: I clicked, I read, and I spiralled.

The study, conducted by researchers at The University of Sydney’s Charles Perkins Centre, asked a deceptively simple question: Can what we eat – just for six weeks – change how old we are on the inside? Not in a 'reverse the clock', Benjamin Button kind of way. No creams. No cryotherapy. No powdered deer antler. Just food. Real food.

"As we age, our health tends to decline. It’s an inconvenient biological truth. This is where the idea of biological age comes in: it doesn’t just measure the passage of time but asks how well your body is holding up under its share of wear and tear."

Dr Caitlin Andrews

To measure this, they used something called the Klemera-Doubal Method (KDM). Sounds like a Cold War cipher, right? Actually, it’s an algorithm. Clever enough to take routine health markers like blood pressure, cholesterol, BMI, and blood cell counts, and crunch them into a single estimate of the age gap between your body and your birth certificate (turns out maths isn’t totally useless). Wild. And this gap? It’s not just dinner party trivia. It’s your body’s risk assessment for future breakdowns: age-related potholes, functional slowdowns, or an early curtain call.

As we age, our health tends to decline (because apparently, life thought saggy knees and random groans would be hilarious). It’s an inconvenient biological truth that explains why standing up during your 'golden years' feels like a high-stakes operation… complete with creaks, cracks, and a standing ovation if you manage it without wincing. This is where the idea of biological age comes in: it doesn’t just measure the passage of time but asks how well your body is holding up under its share of wear and tear.

Whether it's marching, jogging, or wheezing behind the parade.

If your body’s internal age is higher than your actual age, it’s like your organs are ageing ahead of schedule... pulling double shifts under bad management. Think milk left out in the sun. Not great. But if it’s lower, your insides are aging with the grace of a vintage wine: slow, steady, and... smug. And the bigger the gap in the right direction, the better. That's what the researchers were measuring. Whether diet could nudge that gap in the right direction.

Let’s be clear: This algorithm doesn’t tell you how old you are. That’s the job of your birth certificate and the teen at the checkout who calls you 'ma’am'. Instead, it listens to your body’s internal chatter and asks, 'compared to others your age, are you thriving, surviving, or running on fumes?'. It’s not about decoding some mystical 'true age'. It’s about health. The status of your health, in the context of your age. Think of it this way: if chronological age is the number of years, you’ve owned the car, the KDM algorithm gives us the mechanic’s report—all the useful stuf about how well the engine’s running.

The study involved 104 older adults (65-75 years) randomly assigned to one of four tightly controlled diets:

• omnivorous high-fat (OHF): rich in animal protein and fat, not far off the average Aussie plate: meat-heavy, low on legumes, and suspiciously beige - the culinary equivalent of shrugging at your arteries
• omnivorous high-carb (OHC): still omnivorous, but with more whole grains and complex carbs, think meat-eater who’s discovered quinoa and isn’t mad about it
• semi-vegetarian high-fat (VHF): mostly plant-based, with a generous helping of olive oil, nuts, and the occasional cheese cameo, the diet equivalent of a flexitarian who shops at the farmers’ market and says things like ‘I don’t eat meat, except when I do”
• semi-vegetarian high-carb (VHC): the most plant-based and fibre-rich of the bunch, think lentils, legumes, whole grains, and vegetables -basically, if a diet could wear Birkenstocks and compost, it would be this one.

All meals were provided. All health markers were measured. No one was asked to juice celery or chant affirmations to their mitochondria.

The results? The OHF group – whose diet most closely resembled the average Australian diet – showed no significant change in the age gap between body and birth certificate.

But the other three groups, especially those eating more fibre and fewer processed fats, showed improvements. Their bodies started aging more slowly than expected. Not dramatically. But measurably. In just six weeks.

As someone who’s spent years watching the wellness industry sell youth in increasingly absurd packaging – collagen water, mushroom coffee, “anti-ageing” toothpaste – this study felt refreshingly... boring. No superfoods. No supplements. Just more legumes, fewer saturated fats, and a bit of dietary humility.

Of course, the researchers were careful not to overstate their findings. This wasn’t a prescription. It wasn’t a promise. It was a signal – a suggestion that our internal systems might be more responsive to diet than we thought, even in later life.

I called one of the researchers to ask what this all meant. “We’re not saying you can reverse aging. But we are saying that biological age is dynamic. It’s not fixed. And that opens up some interesting possibilities.”

Interesting indeed. Because if biological age is a moving target, then health isn’t just about avoiding disease. It’s about maintaining system integrity. It’s about how well your body adapts. Recovers. Communicates with itself. Something a single biomarker can’t tell you.

The study didn’t test a product. It tested a pattern. A way of eating that emphasized whole foods, complex carbohydrates, and plant-based proteins. The kind of diet that’s been quietly recommended by public health guidelines for decades. In just six weeks, participants on higher-fibre, lower-fat diets showed a meaningful shift (think, dysfunctional family dinner to civil office meeting – still some occasional side-eyes, but everyone’s mostly playing nice).

That’s the kind of result that doesn’t just make headlines. It makes policy advisors sit up straighter in their ergonomic chairs. Because if a short-term dietary intervention can measurably improve the age gap between your body and your birth certificate, what does that mean for aged care nutrition? For chronic disease prevention? For how we talk about healthy aging – not as a luxury, but as a system-level investment?

The implications are quietly radical. This wasn’t a longevity pill. It was lentils. It was fibre. It was minimally processed, whole foods. The kind of stuf that doesn’t promise to “detox your aura”. It was a reminder that the most powerful interventions often look suspiciously like common sense (the one thing that never trends, never sells, and never gets invited to wellness expos). The kind of advice that’s been around since before kale had a PR team.

Even after a lifetime of nutritional misdemeanours… Kellogg's fun packs. Drive-thru dinners. Sodium-fuelled nostalgia. Your body might still be open to negotiation. Turns out, your cells aren’t holding a grudge about the ‘90s. Or the 2000s. Or last Tuesday. Change is possible. Not guaranteed. But possible.

And that possibility matters. Especially in a world where aging is often framed as a decline, a loss, a slow fade to grey. What if we reframed it as adaptation? As resilience? As a system that, with the right inputs, can still surprise us?

As I wrapped up my interview, I asked the researcher what they hoped people would take away from the study. “That health is a system,” they said. “And systems respond to care.”

I liked that. It felt human. It felt hopeful. And it felt like progress. So no, I didn’t rush to upload my bloodwork to a website claiming to reveal if I’m aging like a vintage shiraz or a banana left on a dashboard. At the ripe young age of 49, I don't need tests and wearables to confirm whether I’m biologically 25 or just really good at denial (obviously not the latter). This research wasn’t about turning biomarkers into a horoscope.

It wasn't to offer a tool for self-diagnostics or personalized prophecy. The researchers used biological age as a research tool, not a party trick. they were showing how diet – not ego or fads – can shift the odds. Shift your risk of age-related disease, early functional decline, or an early exit, all relative to the number on your birth certificate.

But I did go and buy some lentils. And now I've started thinking less about the number of candles on the cake and more about whether I can blow them out without needing a nap after. Which, for a chronically curious health nerd who still can’t find their reading glasses without a full archaeological dig, feels like progress.