How to reduce biological age — what the evidence actually supports

The longevity space has a noise problem. Every month there's a new supplement, a new protocol, a new device promising to reverse ageing. Most of it is marketing built on single studies or animal data that hasn't translated to humans.

I want to write about what the evidence actually supports. Not what sells. What I use, what I recommend, and what I've seen move the numbers.

What moves biological age — and what doesn't

The single most powerful lever is something no supplement can replace: metabolic health. Fasting glucose, insulin sensitivity, triglycerides, visceral fat — these biomarkers have the strongest and most consistent relationship with biological age across every major study I've reviewed.

A person with optimal metabolic markers will almost always have a lower biological age than someone the same chronological age with metabolic dysfunction. This is not controversial. It's one of the most replicated findings in the field.

The second lever is systemic inflammation. CRP, IL-6, fibrinogen — chronic low-grade inflammation is a primary driver of accelerated biological ageing. It's also one of the more addressable ones. Diet, sleep, stress physiology, and — in some cases — specific anti-inflammatory interventions can move these markers meaningfully.

Sleep — the most underrated intervention

I've had clients come in with a biological age 6–8 years above their chronological age. We go through everything. And often, the single most actionable finding is sleep — not duration alone, but quality and consistency.

Poor sleep elevates cortisol, disrupts glucose regulation, increases inflammatory markers, and impairs cellular repair. All of these accelerate biological ageing. And yet most people treat sleep as negotiable.

It isn't.

Exercise — but the right kind

Zone 2 aerobic training has the most robust evidence base for longevity outcomes. It improves mitochondrial function, insulin sensitivity, and cardiovascular efficiency — all of which are directly reflected in biological age markers.

Resistance training matters too, particularly for preserving muscle mass and metabolic rate as you age. The combination of both is consistently associated with lower biological age in population studies.

High-intensity exercise has a role. But it is not a substitute for the foundation.

Nutrition — less complicated than it's made to seem

The evidence doesn't support any single dietary dogma. What it does support: adequate protein, minimally processed food, controlled glucose response, and sufficient micronutrient density. These four things, consistently maintained, will do more for your biological age than any supplement stack.

Time-restricted eating has reasonable evidence, particularly for metabolic markers. But the effect size is modest and highly individual. I don't prescribe it universally.

What about supplements

There are a handful with meaningful evidence in humans — not just mice. NAD+ precursors, in the right context and dosing. Omega-3 at therapeutic levels. Vitamin D where deficiency exists. Magnesium. A few others depending on individual biomarker gaps.

But supplements work at the margin. They are not a foundation. I've seen too many people spending significant money on complex stacks while their sleep is poor, their glucose is elevated, and they don't exercise consistently. That's the wrong order of operations.

How to know if what you're doing is working

You measure. Not once — repeatedly. Biological age as a tracked metric over time tells you whether your interventions are actually moving the biology, or whether you're just feeling better subjectively without evidence to support it.

That's the whole point of having a number.