How to Eat for the Next 40 Years: What the Science on Longevity Actually Says

Most nutrition advice is aimed at one goal: losing weight. And while weight management matters, it is not the only thing — or even the main thing — that should be guiding the dietary choices of a man in his 60s who wants to live well into his 90s.

Peter Attia's Outlive was the book that clarified my thinking here. Attia is not interested in helping people lose weight. He is interested in helping people maintain function — physical strength, metabolic health, cognitive sharpness — across a lifespan that might extend to 100. Those two goals require different strategies. And the standard advice about eating less and moving more, while not wrong, is far too blunt to be genuinely useful.

The goal is not to add years to your life. It is to add life to your years — to compress the period of decline at the end rather than extending it.

Here is what I've learned, synthesised from Attia's work and my own experience with 16/8 intermittent fasting over the past two years.

Protein: The Most Underrated Priority After 60

The mainstream advice about protein — eat moderate amounts, don't overdo it — was calibrated for young adults. For men over 60, it is actively misleading.

As we age, our bodies become less efficient at processing dietary protein into muscle. The scientific term is "anabolic resistance." What this means in practice is that a 65-year-old man needs significantly more protein per kilogram of body weight to maintain the same muscle mass as a 35-year-old man. And muscle mass, as I discussed in my post on resistance training, is one of the strongest predictors of longevity and independence.

Attia's recommendation — aligned with most current sports science — is a minimum of 1.6 grams of protein per kilogram of body weight per day. For a man weighing 85 kilograms, that is 136 grams of protein daily. Most men eat perhaps half that.

Good protein sources include eggs, lean meats, fish, Greek yoghurt, cottage cheese, and legumes. The challenge is less about knowing what to eat and more about consistently prioritising it. I have found that planning my main meals around a protein source first — and treating everything else as supporting cast — is the most effective approach.

The Case for (and Against) Intermittent Fasting

I have been following a 16/8 intermittent fasting protocol for about two years — eating within an 8-hour window, typically from noon to 8pm. I find it genuinely effective for managing my eating, simplifying decisions, and maintaining stable energy throughout the day.

Attia's view on intermittent fasting is more nuanced than most advocates allow. He acknowledges the real benefits — improved insulin sensitivity, potential support for cellular repair through a process called autophagy, and the simple practical benefit of eating less by having fewer opportunities to eat. But he also warns against a specific trap that many older men fall into: using intermittent fasting in a way that makes it difficult to eat enough protein.

If you're skipping breakfast and eating within an 8-hour window, you have eight hours to consume 130+ grams of protein. That requires real intention. It is very easy to end up under-eating protein while believing you're eating healthily, which progressively accelerates the muscle loss that threatens your independence in later decades.

The resolution is simple but requires attention: if you practise intermittent fasting, build your meals around protein first and make sure you're hitting your daily target, even within the shorter window.

Blood Sugar, Insulin, and the Silent Epidemic

Type 2 diabetes and insulin resistance are not diseases that appear suddenly. They develop over decades, driven by the cumulative effect of blood sugar spikes, excess carbohydrate intake beyond what your muscles can absorb, and insufficient physical activity. By the time a man is diagnosed at 65, the process often began at 45.

What Attia emphasises — and what I find genuinely clarifying — is that managing blood sugar is not only about avoiding diabetes. Chronic insulin resistance is associated with accelerated cognitive decline, increased cancer risk, and cardiovascular disease. The metabolic system is upstream of almost everything else that kills men in their 70s and 80s.

Practical strategies that work, grounded in the evidence:

• Walk after meals. Even a 10-minute walk after eating meaningfully reduces the blood sugar spike from that meal. This is one of the simplest, most effective interventions in metabolic health.
• Prioritise fibre. Vegetables, legumes, and whole grains slow the absorption of glucose, reducing spikes.
• Limit processed carbohydrates and added sugar. Not because carbohydrates are evil, but because the refined versions drive blood sugar volatility with almost no nutritional benefit.
• Eat protein and vegetables before starchy foods. The sequence in which you eat food at a meal affects the blood sugar response. Protein and fat first, starches last, meaningfully flattens the curve.

What I Actually Eat — And the Simple Principles Behind It

I want to be clear that I am not following an exotic or complicated dietary protocol. The fundamentals I have arrived at are neither new nor surprising. They are simply applied consistently.

My day typically looks like this: I skip breakfast (intermittent fasting). Lunch is built around protein — fish, chicken, or eggs — with plenty of vegetables and some good fats. Dinner follows the same pattern. I eat fruit in the afternoon. I drink mostly water and black coffee. I avoid processed foods and alcohol during the week.

What has changed is not the food itself but the intentionality. I think about what I am eating in terms of what it is building or protecting, not just whether it tastes good or whether I'm hungry. That shift in framing — from comfort to construction — is, I think, the most important dietary change a man in his 60s can make.

You are not eating for the body you have today. You are eating for the body you will need at 80.

The science on longevity nutrition is more settled than the endless dietary debates suggest. Eat enough protein. Protect your blood sugar. Minimise ultra-processed foods. Move after meals. These are not controversial positions — they are the evidence-based consensus that every serious researcher in the field has arrived at independently.

The challenge is never knowledge. It is consistency. Start with one change — protein first at every meal — and build from there.

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