Luka Modrić and the Secret of Athletic Longevity: Your Metabolic Age Matters More Than Your ID

As the entire world turns its attention to the 2026 World Cup, one name keeps coming up with admiration: Luka Modrić. At 38 and pushing 39, the Croatian midfielder is still competing at the highest level of world football, an age at which most players hung up their boots long ago. As publicly reported, Modrić is one of the oldest elite footballers still active, widely recognized for his professionalism, his disciplined lifestyle, his meticulous attention to nutrition and recovery, and a notably low body-fat percentage.

The question many people ask is not only how he does it, but what his case teaches us about something all of us can take care of: the difference between chronological age (the number on your ID card) and metabolic age (how old your body actually functions on the inside).

The age on your ID vs the age of your body

Chronological age is a fixed number: how many years have passed since you were born. We can't change it. Metabolic age, on the other hand, is a concept that describes how young or how aged your body operates at the cellular and hormonal level, regardless of the number on your documents.

Two people who are both 40 can have bodies that function in radically different ways. One may have the physiology of someone in their early 30s; the other, that of someone in their mid-50s. What drives that difference isn't luck or genetics alone, but a combination of metabolic factors that, to a meaningful degree, can be influenced by lifestyle.

The pillars of a young metabolic age

When we talk about a body that functions "young," general physiology points to several key markers that, according to the scientific literature, tend to go hand in hand:

Insulin sensitivity. Insulin is the hormone that helps blood sugar enter your cells to be used as energy. When the body responds well to insulin, it regulates glucose efficiently. When that sensitivity deteriorates (insulin resistance), the body enters territory associated with accelerated metabolic aging.

Low visceral and liver fat. Not all fat is the same. Visceral fat (the fat surrounding your organs) and fat stored in the liver are linked, according to research, to poorer metabolic function. A body with little visceral fat tends to behave "younger." It's no coincidence that elite, long-lasting athletes are publicly reported to carry a low body-fat percentage.

Muscle mass. Muscle isn't just strength: it's a metabolically active organ that helps manage glucose and supports your metabolism as you age. Preserving muscle mass is one of the most studied factors in longevity.

Mitochondrial health. Mitochondria are the "power plants" of your cells. Healthy mitochondria mean cells that produce energy efficiently, something physiology associates with slower aging.

The liver: the forgotten organ of metabolic age

Here's the point many people overlook. The liver is the great conductor of the metabolic orchestra, and its condition carries enormous weight in how your body "ages" on the inside.

Glucose regulation. The liver stores and releases sugar to keep your levels stable between meals. When the liver is overloaded with fat, that regulation becomes less precise.

Thyroid hormone conversion (T4 to T3). A significant portion of the conversion of thyroid hormone T4 (the storage form) into T3 (the active form that revs up your metabolism) happens in the liver. A well-functioning liver supports an active metabolism; a compromised liver can leave that conversion running at half power.

Detoxification. The liver processes and clears substances the body needs to filter out. It's a central piece of internal balance.

That's why, in the Salinas Method approach, the liver takes center stage: taking care of your liver is, to a large extent, taking care of your metabolic age. If you want to understand in depth how this organ is evaluated and cared for, you can read about the liver ultrasound, one of the most revealing tools for looking at what's happening inside.

How all these factors interlock

Something worth understanding is that these pillars don't act in isolation: they form a system. Fat stored in the liver can worsen insulin sensitivity; poorer insulin sensitivity makes it easier to store even more fat; and that loop ends up affecting energy levels, body composition, and, according to physiology, how quickly the body "ages" on the inside.

The good news is that the loop also works in reverse. When liver fat goes down and insulin sensitivity improves, muscle works better, available energy increases, and the metabolism as a whole tends to behave more efficiently. It isn't about a single "trick," but about a balance built through habits sustained over time, which is exactly what's publicly reported about long-lasting athletes: they don't improvise, they tend to these details year after year.

Everyday energy is also a signal

You don't need a laboratory to notice general signs of how your metabolism is functioning. Stable energy throughout the day, restful sleep, the ability to recover after exertion, and a sense of mental clarity are, broadly speaking, reflections of a metabolism that is working in your favor. When those elements persistently fail, it's often worth looking deeper, and that's where the liver and metabolic markers take center stage. Keep in mind that these are general educational observations and never replace a professional evaluation.

So what does the Modrić case teach us?

We have no access to the private medical data of any footballer, and we don't need it. What is publicly reported is that the athletic longevity of players like Modrić is built on foundations of discipline: attention to nutrition, recovery, rest, managing physical stress, and a carefully maintained body composition year after year.

Those same pillars are, not by coincidence, the ones that general physiology associates with a younger metabolic age. The great news for the rest of us is this: you don't have to be an elite athlete to start taking care of your metabolism. The principles are the same at any scale.

You can be younger than your ID card

The central takeaway worth carrying home is liberating: the number on your documents does not dictate how your body functions. By supporting your insulin sensitivity, reducing visceral and liver fat, preserving your muscle mass, and above all caring for the health of your liver, it's possible for your body to function younger than your chronological age would suggest.

If you want to go deeper into how to organize your nutrition and lifestyle around liver and metabolic health, you can explore the Salinas Method books, where this entire approach is developed step by step.

Modrić is a public, visible reminder that, with the right care, the body can perform far beyond what its age might suggest. And while most of us will never play in a World Cup, we all share the same goal: making our metabolic age work in our favor.

Disclaimer: This content is educational and intended as general physiology information. It is not individual medical advice or a diagnosis, and all information about Luka Modrić is based solely on publicly reported facts. For decisions about your health, always consult a qualified healthcare professional.