Getting real about getting lean.

The GOAT, Jan Frodeno, was not carrying a whole lot of extra baggage with him on his way to 3 World Titles…

Felix Sanchez Arrazola | Alamy

No area of high-performance sport is more clouded by misinformation than body composition. Few topics invite as much emotional baggage, cultural bias, and pseudo-scientific nonsense as discussions about body fat, weight, and what an “ideal” physique really looks like for elite endurance performance.

When we combine excessive political correctness with good old-fashioned laziness, there’s very little room left for real talk — about what actually works, what doesn’t, and what it really takes to achieve a body composition that supports world-class endurance.

That’s exactly what this post aims to do. No fluff, no moralizing — just the physiological facts and practical realities behind two essential questions:

1️⃣ What is an ideal level of body fat if our goal is high-performance endurance sport?
2️⃣ What is the best way to get from where we are now to there?

Let’s begin by grounding the discussion in data:

What are typical body composition numbers for top endurance athletes?

We’ll start by reiterating a simple truth — one that’s often inconvenient, but undeniable: the best endurance athletes tend to be very lean.

There’s a reason for that. Carrying extra mass, whether fat or unnecessary muscle, simply costs energy. In a sport defined by how efficiently you can move your body over long distances, every gram matters. The physiology is clear - leanness improves running economy, cycling power-to-weight ratio, and your ability to manage heat. In short: less non-functional mass equals more performance.

In Chapter 8, we looked at how body composition tends to break down across different sports and disciplines — from power-dominant events to pure endurance. Let’s now zoom in on the endurance end of that spectrum and look at what the numbers actually tell us.

For men…