Fuel for the Wild: Mastering Fat Adaptation for Trekking and Ultra-Running

Introduction: Picture the Possibility

You’re five hours into a demanding trail, surrounded by jagged peaks and endless vistas. Your pack feels lighter than it should, your legs are steady, and your mind is sharp. While others rummage for energy gels, you press on with unwavering energy. What’s your secret? It’s not magic or the latest energy bar—it’s your body, finely tuned to burn fat for fuel.

Back when I was a youth I’d hit “the wall” on long hikes and runs, feeling drained, foggy, and defeated. Like many, I thought the answer was eating more carbs, but no matter how many snacks I packed, fatigue would catch up. It wasn’t until I started training my “fat engine” that I found a steady, almost limitless energy source—and it transformed the way I approached endurance.

Let’s dive into how you can get back to using our bodies main and natural fuel source, enhance your resilience, and dominate the trails like never before.

Why Fat is Your Adventure Superpower

Your body is like a hybrid car with two fuel systems:

  1. Glycogen (Carbs): A fast-burning but limited fuel, like a high-octane turbocharger.
  2. Fat: A slower-burning, near-infinite energy source—perfect for anything that needs endurance.

While glycogen burns quickly, fat is the ultra-efficient backup your body often overlooks. The key is training your system to prioritize fat, enabling you to conserve glycogen for critical moments—like that final summit push.

The Road to Fat Adaptation: Building Your Fat Engine

1️⃣ Fasted Training: Start Your Day Running on Empty

The simplest way to encourage your body to burn fat is to train on an empty stomach. Think of it as teaching your metabolism to dig deeper when glycogen is low. Early morning runs before breakfast are perfect for this.

How I Learned the Hard Way:
I remember when I first incorporated fasted training into my routine. It wasn’t pretty, at first my performance dropped ie my initial weekday fasted runs were slower, but this is natural. But by sticking with it, my body adjusted, and I began feeling stronger and more energized during my long weekend efforts, and I found I was having to refuel less.

Your Action Plan:

  • These are your weekday efforts not your big weekend sessions
  • Start with 30-45 minutes of low-intensity runs.
  • Keep intensity light—you should be able to chat without gasping.
  • Build up to 90 minutes over a few months.

2️⃣ Zone 2 Training: The Steady Burn

Zone 2 is your fat-burning sweet spot. By training at 65-75% of your maximum heart rate (180 minus your age), you condition your body to use fat as its primary energy source. It’s the cornerstone of endurance training.

A Trekker’s Secret Weapon:
When prepping for a multi-day trek in New Zealand, one of my clients, Emma, committed to three week day Zone 2 sessions. Over a period of 12 weeks, not only did her stamina improve, but she also felt she finished her sessions with energy to spare.

Your Action Plan:

  • Use a heart rate monitor to track your pace.
  • Engage in activities like running, cycling, or pack hiking.
  • Gradually extend sessions from 30 minutes to 90 minutes.

3️⃣ Eat Like a Fat-Burner

Nutrition plays a pivotal role in fat adaptation. Think of it as fueling the right system—what you eat directly affects whether your body burns fat or glycogen.

The Fat-First Diet:
During training blocks, I shift to a low-carb, high-fat (LCHF) diet: Fatty cuts of meat, creamy avocados, some oily fish, and the occasional handful of macadamia nuts. For high-intensity days, I reintroduce carbs like sweet potatoes to replenish my glycogen stores.

Your Action Plan:

  • Fats to Focus On: Fatty cuts of meat as the primary go to, followed by Avocado, nuts, seeds, olive oil, fatty fish.
  • Earn Your Carbs: Carbs like sweet potato on strength training days and after high intensity sessions. Use carbs sparingly when doing long weekend sessions just to top up the fuel tank on those extended sessions. 
  • Hydration Hack: Add a little Himalayan or celtic salt to your water to maintain electrolyte balance.

Real-Life Transformation: Peters Journey 

Peter, a 60-year-old adventurer, came to me for advice to help him train for the Haute route, but he also wanted to train for longevity. As well as his training one of the things we slowly implemented was a fat-adaptation strategy: fasts, LCHF nutrition, and Zone 2 training. Peter is loving it, he’s unstoppable. Peter, an ex- royal marine, was already fit but His metrics have improved in all areas. He’s lost body fat, increased lean muscle mass, his VO2 max, his endurance and his time to fatigue have all improved.

He told me, “I’m fitter now than I have ever been since I left the marines” Now that is saying something!

The Payoff: Fat Adaptation in Action

When you’re fat-adapted, you gain:

    1. Enhanced Energy and Endurance: Fat adaptation provides a steady energy source, supporting extended physical performance without energy crashes.
    2. Improved Fat Burning and Weight Management: It increases the body’s ability to burn stored fat, aiding in fat loss and weight control.
    3. Stable Blood Sugar Levels: It helps maintain consistent blood glucose levels, reducing energy dips and sugar cravings.
    4. Potential Anti-Aging Effects: Fat adaptation may activate enzymes linked to longevity and reduced cellular aging.
    5. Enhanced Metabolic Flexibility: It allows the body to efficiently switch between fats and carbs, improving metabolic health and adaptability.
    6. Improved Mental Clarity: Fat adaptation stabilises blood sugar levels, reducing brain fog and enhancing focus and cognitive function.

What’s Your Next Step?

Training your fat engine isn’t a sprint—it’s a slow, steady climb. But like all great adventures, the journey is worth it. Start small, stay consistent, and pay attention to how your body responds.

So, what fuels your adventures right now? Are you relying on quick carbs, or have you experimented with fat adaptation? I’d love to hear your experience—drop your thoughts in the comments below!

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