📊 What Happened to My Body After 36 Days on the GR10 (and Setting an FKT!)

This summer I hiked the entire GR10 across the French Pyrenees — 955 km with over 53,000m of elevation gain.

It took me 36 days, 5 hours and 28 minutes, and I set the first female Fastest Known Time (FKT) for the route.

But I was curious… what did 36 days of hiking do to my body?

Before I left, I used my Hume smart scale to record baseline measurements.

As soon as I returned, I repeated the scan.

The results gave me a fascinating picture of how my body adapted to the challenge — here’s the breakdown.

📉 Weight and Fat Loss

• Weight: 70.7 kg → 66.5 kg (−4.2 kg)

• Body Fat %: 28.6% → 24.7% (−3.9 percentage points)

• Fat Mass: 20.2 kg → 16.4 kg (−3.8 kg)

  
  

👉 The big story is fat loss. Nearly all the weight I lost was fat — around 19% of my starting fat mass.

That’s exactly what you’d expect after sustained high-volume hiking with a big pack day after day.

💪 Lean Mass and Muscle

• Lean Mass: 47.4 kg → 48.5 kg (+1.1 kg)

• Skeletal Muscle Mass: 29.0 kg → 31.5 kg (+2.5 kg)

• Body Cell Mass: 33.1 kg → 35.1 kg (+2.0 kg)

  
  

👉 Surprisingly, my lean mass went up. Scales aren’t perfect at measuring muscle, but the trend suggests I preserved or even gained muscle from all the climbing, descending, and carrying my pack.

💧 Hydration

• Body Water: 52.1% → 58.7% (+6.6%)

  
  

👉 My hydration status improved significantly. Bioelectrical scales are very sensitive to water — so some of the muscle gain reading is likely linked to being better hydrated post-trail.

But it still shows I came back in a healthier state.

❤️ Heart and Metabolism

• Resting Heart Rate: 95 bpm → 73 bpm (−22 bpm)

• Metabolic Age: 45 yrs → 40 yrs (−5 yrs)

• Visceral Fat Index: 9 → 8

  
  

👉 This was one of the most encouraging shifts. My cardiovascular fitness improved dramatically, my metabolic “age” dropped, and my visceral fat (linked to health risks) went down too.

🔍 The Bigger Picture

Hiking the GR10 wasn’t about weight loss or body changes — it was about the challenge, the adventure, and proving what’s possible.

But it’s fascinating to see how the body adapts to 36 days of endurance activity:

• Fat burned,

• Muscle preserved,

• Cardiovascular fitness boosted,

• Hydration and cellular health improved.

It shows just how powerful moving your body every day can be.

Final Thoughts: If you’re thinking about your own adventure — whether it’s a long-distance trail or just getting outside more regularly — know that your body is capable of incredible adaptation.

For me, the GR10 wasn’t just about an FKT — it was about coming back stronger, inside and out.

Learn more about the GR10 Hike - Read the blog posts here.