In a world where wellness trends evolve faster than evidence can keep up, clarity rooted in science has never been more valuable. At the intersection of cutting-edge research and real-life application stands Professor Sarah Berry, Professor of Nutritional Sciences at the Department of Nutritional Sciences within the School of Life Course Sciences, Faculty of Life Sciences & Medicine.

Renowned for her pioneering work in personalized nutrition and metabolic health, Professor Berry is reshaping how we understand the relationship between food, lifestyle, and long-term wellbeing. Her research challenges one-size-fits-all approaches, offering a more nuanced, data-driven perspective on how individuals respond differently to the same foods.

In this exclusive Porterium Magazine feature, we explore Professor Berry’s insights into preventive health, the future of nutrition science, and how modern lifestyles can be recalibrated to support longevity, vitality, and performance at the highest level.

Q: Intermittent fasting, keto, plant-based — which trends are actually supported by science, and which are overhyped?

Professor Sarah: “Some diet trends do have a scientific basis, but none is a silver bullet – and large-scale research is helping us understand why.

Take intermittent fasting. Many clinical trials show that reducing your eating window to 6-8 hours improves metabolic health and can help with weight loss. However you don’t have to be that restrictive; our ZOE Big IF Study, the largest real-world study of its kind, show that a simple 10-hour eating window can improve energy, mood, hunger, and digestive symptoms for many people. But there’s clear variability – not everyone responds in the same way, and factors like lifestyle matter.

The science around Keto is very mixed. Whilst keto diets may lead to short-term weight loss, it’s often difficult to sustain and can crowd out many beneficial plant foods. In contrast, diets rich in plants have the strongest and most consistent evidence for long-term health – but importantly, this isn’t about strictly excluding animal products. What the data consistently show is the value of diversity: aiming for 30 or more different plant foods each week – including nuts, seeds, legumes, herbs, and spices – helps support a healthier, more resilient gut microbiome and improves overall health.

It’s also important to remember that we are all human. Nutrition isn’t just biology – it’s also about enjoyment, culture, and sustainability. I often say that if you’re not enjoying what you’re eating, then it’s not healthy at all. The goal is to find an approach that works for you – one that you can sustain and genuinely enjoy over the long term.”

Q: Is there such a thing as a universally “optimal diet,” or is personalization now essential?

Professor Sarah: “We’ve really moved beyond the idea that there’s a single ‘optimal’ diet that works for everyone. What the science now shows us – particularly from large-scale trials like our ZOE PREDICT studies – is that people can have remarkably different responses to the very same foods.

Our ZOE data showed that even identical twins can have very different blood sugar and blood fat responses to identical meals. That tells us that while genetics plays a role, they’re only part of the story. Factors like the gut microbiome, sleep, physical activity, and even the timing and order of meals all influence how our bodies respond.

So while it is important to remember that there are some clear fundamentals – such as eating a diet rich in whole, minimally processed foods, particularly plants – there’s no one-size-fits-all approach. Personalization is key if we want to truly optimize health.”

Q: Many high-performing individuals experience fatigue despite eating “well” — what are the hidden nutritional mistakes you see most often?

Professor Sarah: “A key mistake is not recognising that the 4 pillars of health are interconnected; sleep, diet, physical activity and stress. For example, if you have a poor nights sleep, the reward centres in your brain are activated, encouraging you to select high sugar foods and to overeat. Studies show that sleep deprivation can result in the consumption of an extra 400kcal! 

Another key mistake is not recognising how food can impact how we feel in the here and now. For example, postprandial glycaemic dips, or blood-sugar dips, can leave you feeling foggy, tired and wanting to snack more. Our ZOE research published in Nature shows that around 25-30% of people experience what we call a ‘glucose dip’ after eating a carbohydrate-rich meal, where blood sugar falls below baseline a few hours after eating.

These dips are strongly linked with how people feel – lower blood sugar is associated with reduced alertness, increased fatigue, and a greater drive to seek out food sooner than they otherwise would.

We’ve also found that individuals who fall into this “dipper” pattern tend to respond differently after higher-carb meals: they often feel hungry again more quickly, go on to eat slightly more at their next meal (around an extra 100 calories on average), and may consume roughly 300 additional calories across the day as they try to compensate for that post-meal energy drop.

I’ve seen this not just in research, but in real life too. I used to experience that classic mid-afternoon slump – feeling tired, irritable, and reaching for something sugary. When I looked more closely, it became clear that blood sugar dips were playing a big role. Small changes, like shifting towards a breakfast with more protein, healthy fats, and fiber, made a noticeable difference to my energy and focus across the day. You want more of a gentle rise and fall in energy – not dramatic spikes and crashes that leave you feeling depleted.”

Q: In today’s fast-paced lifestyle, what are the best snacks one should keep on their desk or in their bag to maintain stable energy levels and avoid reaching for quick sugar fixes?

Professor Sarah: “Nuts are one of the simplest, most evidence-based snacks I recommend people keep on hand.

They’re packed with so many great nutrients – healthy unsaturated fats, fibre, and protein – which together make them both nourishing and satisfying. They’re also a source of important micronutrients like vitamin E, magnesium, and selenium, which play roles in everything from energy metabolism to protecting cells from oxidative stress.

What I find particularly interesting from my research on nuts is that they’re not just a ‘sum of their nutrients’ – their structure matters too. Because of their natural food matrix, with intact plant cell walls, they behave differently in the body compared with more processed foods. That structure influences how nutrients are released and absorbed, which is part of why nuts can feel so sustaining.

We also see benefits beyond immediate nutrition. Regular nut consumption is consistently associated with improvements in cardiovascular health markers, and they provide fibre that supports a healthy gut microbiome. My own research shows that snacking on nuts instead of typical UK or US snacks can improve blood vessel function in as little as 6 weeks and results in a predicted 30% reduction in cardiovascular disease.

So as a practical snack, a small handful of mixed nuts is hard to beat. They’re portable, require no preparation, and they offer a really dense package of nutrients that support long-term health.”

Q: Are there specific dietary patterns linked to long-term brain performance?

Professor Sarah: “Dietary patterns that emphasize plant diversity, healthy fats and minimally processed foods are consistently associated with better cognitive health over time. In particular, diets rich in vegetables, whole grains, legumes, nuts, seeds, and omega-3 sources such as oily fish appear to support both brain function and long-term brain health. The Mediterranean diet is a good example of this kind of eating pattern.”

Q: What are the most effective nutritional strategies for women over 40 to support hormonal balance and slow down biological aging?

Professor Sarah: “At ZOE, we ran the world’s largest in-depth study into the impact of nutrition on menopause. We found that menopause is a key transition in women’s metabolic health, associated with changes in blood sugar, blood pressure, body fat, sleep, and cardiovascular risk. Importantly, these changes are influenced not only by hormones, but are also linked with diet and the gut microbiome.

For women over 40, the most effective nutritional strategies focus on supporting metabolic health rather than targeting “hormonal balance” alone.

The advice is similar at all ages: a diverse, plant-rich diet centered around whole foods – including vegetables, fruit, legumes, whole grains, nuts and seeds.

It’s also important to support stable blood sugar responses, which can become more variable during and after menopause. Choosing higher-fibre, less processed foods can help with this.

Whilst most of us get more than enough protein, protein needs do go up slightly as we age. Protein is key for maintaining muscle mass, which naturally declines with age and plays an important role in metabolic health and healthy ageing. Healthy fats, particularly from sources like oily fish, nuts and seeds, support cardiometabolic health.”

Q: ZOE is leading large-scale research combining AI and nutrition — how should individuals balance scientific recommendations with their own body awareness?

Professor Sarah: “Science provides a powerful foundation, and it should complement – not replace – individual awareness. Data can help identify patterns and guide better choices, but it’s equally important to pay attention to how you feel: your energy levels, satiety, and mood. The most effective approach is one that combines scientific insight with an understanding of your own body’s responses.”

Q: What are the most important foundational principles of nutrition that every child should learn from an early age?

Professor Sarah: “From an early age, the most important thing is to help children build a positive relationship with food. That means encouraging curiosity and enjoyment of a wide range of foods. The more diverse their diet is in childhood – particularly with whole, minimally processed foods – the better.”

Q: If you had to name three non-negotiable principles for longevity through nutrition, what would they be?

Professor Sarah: “First, prioritise whole, minimally processed foods and a wide diversity of plants. Aiming for a broad range of fruits, vegetables, beans and pulses – ideally around 30 different plants a week.

Second, reduce heavily processed unhealthy foods where possible. But it’s important to remember that not all processed foods are created equal, which is where tools like the ZOE Processed Food Risk Scale can be helpful. Rather than focusing solely on the degree of processing, it evaluates foods based on factors such as energy density, hyperpalatability, and additives, to better reflect how a food is likely to impact health.

And third, support your metabolic health through everyday behaviours: avoid late-night eating where possible, slow down at meals, and choose better-quality snacks when needed, such as nuts or berries rather than highly processed alternatives. These simple patterns can meaningfully improve appetite regulation and long-term health outcomes.”

In a world of ever-changing diet trends, Professor Sarah Berry reminds us that true health lies not in extremes, but in balance, personalization, and sustainability. Backed by cutting-edge research, her approach highlights the power of plant diversity, metabolic awareness, and simple, consistent habits that support long-term wellbeing. Ultimately, nutrition is not just about science, but about creating a way of eating that you can enjoy and maintain—because lasting health is built on what works for you.