Nutrition: The Foundation of Metabolic Health

The café smells of fresh coffee and something sweetly artificial—probably those pastries under the glass dome that've been sitting there since yesterday. I'm sitting across from Sarah, a brilliant software engineer who's just told me her latest blood work shows she's pre-diabetic. She's thirty-four. "But I count every calorie," she says, stirring her oat milk latte with a certiain precision. "I track my macros religiously. I don't understand what's wrong with me." Nothing's wrong with you, I want to tell her. But I know that's not the whole story she needs to hear. This conversation happens more often than you might think. Intelligent, health-conscious people following all the "rules" they've been taught, yet their bodies seem to be speaking a different language entirely. And here's what I've learned after decades of studying nutrition and metabolic health: we've been having the wrong conversation about food altogether.

When Food Becomes Information

"Let me ask you something," I say to Sarah, leaning forward. "What did you have for breakfast?" She brightens—this is familiar territory. "Protein bar. Twenty-two grams of protein, only twelve grams of carbs, one hundred and eighty calories exactly." I nod. "And what was the first ingredient?" A pause. "I... I'm not sure. Some kind of protein isolate?" Here's the thing we're only just beginning to understand: every single bite you take is having a conversation with your genes. Not just providing calories for energy, but sending complex molecular messages that influence how your cells behave, how your hormones respond, and how your metabolism functions.

Dr. Valter Longo, who runs the Longevity Institute at USC, puts it brilliantly:

"Nutrients communicate with our genes, controlling their expression and can significantly impact metabolic health, ageing, and disease risk."

But what does this actually mean for your morning routine? Let me share what happened when I decided to test this myself. For two weeks, I ate exactly the same calories and macronutrients for breakfast—but from completely different sources. Week one: processed protein bar, instant oats with artificial sweetener, and a handful of almonds. Week two: steel-cut oats cooked with cinnamon, a handful of fresh berries, and a tablespoon of ground flaxseed. Same calories. Same protein, carbs, and fats. Completely different conversation with my metabolism. The continuous glucose monitor I wore told a fascinating story. The processed breakfast? Blood sugar spike that looked like the Shard piercing London's skyline, followed by a crash that left me hunting for snacks by ten-thirty. The whole food breakfast? Gentle rolling hills. Steady energy. No mid-morning desperately eyeing the biscuit tin.

This isn't just about blood sugar, although that matters enormously. Research published in Cell Metabolism shows that two identical-calorie diets can produce dramatically different metabolic responses based purely on food quality and processing level. Your genes are listening to every ingredient, every preservative, every artificial compound, and responding accordingly. Once you know a bit more on the subject, all seems so logical.

Fibre, fibre and again fibre

But here's where it gets really interesting. And this is something I wish I'd understood earlier in my career. I'm standing in my kitchen on a Sunday morning, preparing what my family lovingly porridge: a mixture of oats, ground flaxseed, chia seeds, and whatever berries are in season. My daughter wrinkles her nose. "Why can't we just have normal cereal?" Because, I explain, this "weird" mixture contains something that processed cereals largely ignore: fibre. Not just any fibre, but the kind that feeds the trillions of good bacteria in your belly and makes them happy. We want that, don’t we?

Dr. Michael Greger explains it this way in How Not to Die:

"Fibre isn't just inert roughage; it feeds our gut flora, which then produce compounds like short-chain fatty acids that help regulate our metabolism and immune system."

In short, when your gut bacteria ferment fibre, they produce compounds like butyrate that directly improve how your mitochondria(the power plants in your cells) function. They reduce inflammation. They strengthen your intestinal barrier, preventing toxins from entering your bloodstream and triggering systemic inflammation. The average person gets about fifteen grams of fibre daily. The research suggests we need 25 to 30 grams. That gap? It's not just about digestive health, it's about fundamentally different metabolic conversations happening in your body.

Protein, how much?

"How much protein do I actually need?" Sarah asks, and I can hear the confusion in her voice. She's been told everything from "as much as possible" to "hardly any" — depending on which corner of the internet she's visited recently. This takes me back to a conversation I had with my own GP a few years back. I'd been feeling sluggish, despite what I thought was an optimal diet. Blood work showed everything was "normal," but I wasn't feeling normal. "Tell me about your protein intake and sources,” she said. And the last part got quite interesting - I was getting very little from actual, recognisable food, mostly due to laziness (less cooking, convenience….).

Dr. Longo's research suggests that for most adults, we need roughly 0.8 grams of protein per kilogram of body weight — that's about 56 grams for a 70-kilogram person. Slightly more if you're older or very active. But here's the crucial bit: the source matters enormously. His team's research on centenarians shows that protein consumption influences something called mTOR signalling—a cellular pathway that affects growth, ageing, and autophagy (your cells' cleanup process). Plant proteins, particularly from legumes, seem to support muscle maintenance whilst avoiding the potential metabolic issues associated with excessive animal protein consumption. The difference isn't just academic. When I shifted towards getting most of my protein from lentils, chickpeas, hemp seeds, and the occasional bit of fish, that sluggish feeling lifted. My energy became more consistent. And interestingly, my sugar cravings diminished.

A colourful pharmacy

There's a moment every summer when I'm at the local farmers market, surrounded by the most extraordinary display of colours you've ever seen—deep purple aubergines, bright orange carrots, emerald kale, ruby red tomatoes—and I'm struck by a simple truth: this is a pharmacy. Research has identified more than 25,000 bioactive compounds in plant foods. These aren't just antioxidants (though they are that too). They're signalling molecules that communicate directly with your genes, influencing everything from inflammation to energy production. Take cruciferous vegetables—broccoli, cauliflower, Brussels sprouts, kale. They contain a compound called sulforaphane that activates something called Nrf2, a protein that regulates your body's antioxidant production and cellular defence systems. Eating these vegetables literally enhances your mitochondrial function whilst increasing glutathione production—your body's primary antioxidant. Or berries. Controlled trials show that their polyphenol content can improve insulin sensitivity and reduce those post-meal glucose spikes. Dark leafy greens provide nitrates that enhance mitochondrial efficiency and improve blood flow. But here's what I find most compelling: you don't need to understand the biochemistry to benefit from it. You just need to eat a variety of colourful, whole plant foods. Your genes will sort out the rest.

The timing revolution

Last year, I experimented with something that initially felt quite radical: I stopped eating breakfast. Not permanently—don't panic. But I compressed my eating into a ten-hour window, from noon until ten at night. This is called time-restricted eating, and the research is remarkable.

Dr. Longo explains:

"Periodic fasting-mimicking diets have been shown to promote metabolic and cellular protection, regeneration, and rejuvenation in mice and humans." But you don't need to fast for days to see benefits. A randomised controlled trial published in Cell Metabolism found that participants who ate the exact same foods but compressed their eating window to ten hours showed significant improvements in glucose control, blood pressure, and markers of oxidative stress compared to those eating over fourteen-plus hours. The mechanism is fascinating: fasting periods trigger metabolic switches that shift your body from glucose-burning to fat-burning, producing ketones that serve as both efficient fuel and signalling molecules that regulate inflammation and gene expression. After two weeks of this experiment, I noticed something unexpected. My energy was more stable throughout the day. That three o'clock energy crash that had plagued me for years? Gone. My sleep improved. And rather counterintuitively, I found myself making better food choices during my eating window.

The reality is messier

But let me be honest with you about something. All of this sounds lovely in theory, doesn't it? Eating rainbow vegetables, timing your meals perfectly, getting optimal fibre intake. The reality is messier. Imagine a single father or mother working two jobs who barely has time to microwave a ready meal, let alone prepare elaborate whole-food dishes. Or an old person, on a fixed pension, watching every penny and seeing how expensive fresh vegetables can be compared to processed alternatives. This is where the conversation gets complicated. Because whilst the research is clear about what constitutes optimal nutrition, the ability to implement that nutrition is deeply influenced by time, money, energy, and access. However, even in these hard situations something can be done. That single parent can add a handful of frozen vegetables to that microwave meal (often cheaper than fresh and just as nutritious). The pensioner can choose canned beans over processed snacks, and so on. Even switching from white bread to whole grain, or drinking water instead of sugary drinks, moves the metabolic needle. The goal isn't to overhaul everything overnight—it's to find the one small change that fits your life right now.

I want to add this quote from Dr. Victor Montori, as it reflects the reality pretty well:

"Healthcare that focuses solely on individual responsibility without addressing contexts and constraints is fundamentally insufficient."

The Path Forward

So where does this leave us? "Start with one change, for now" I said to Sarah. "Just one." For her, it was swapping that processed protein bar for steel-cut oats with a handful of berries and a tablespoon of seeds of her choice. Same breakfast routine, completely different molecular conversation.

A landmark study in the New England Journal of Medicine demonstrated that even after decades of suboptimal nutrition, measurable improvements in metabolic markers can appear within days to weeks of dietary changes. Our bodies (and buddies) are extraordinary and we should give them the love they deserve.

Here's what decades of research, combined with real-world experience, has taught me about optimising this conversation:

- Diversify your plant intake. Research shows that consuming thirty different plant foods weekly significantly enhances microbiome diversity, which correlates with improved metabolic markers. This isn't as complicated as it sounds—herbs, spices, nuts, seeds, fruits, vegetables all count.

- Minimise the ultra-processed. When possible, choose foods that look like they did when they grew. Your genes recognise these molecular signatures and respond accordingly.

- Consider your eating window. Even a consistent twelve-hour overnight fast shows metabolic benefits. Greater improvements appear when the eating window narrows to eight to ten hours.

- Focus on food quality over strict ratios. Systematic reviews consistently show that food quality often matters more than precise macronutrient ratios for metabolic health outcomes. But remember: this isn't about perfection. It's about progress. It's about understanding that every single meal is an opportunity to have a better conversation with your metabolism. The nutrition-metabolism connection confirms what traditional wisdom has long suggested: food isn't just calories to be counted or macros to be tracked. It's information. It's communication. It's the fundamental programming language of cellular function, gene expression, and ultimately, your health trajectory.

Your next meal is waiting. What conversation will you choose to have?