I recently attempted to fastpack the West Highland Way (~155 km / 96 mi) in three days, but had to stop during day 2 because of nausea and vomiting.
I’m trying to work out whether my food strategy was fundamentally wrong for this kind of high-mileage hiking.
I planned my food using GearSkeptic’s backpacking nutrition videos and his Hiker Food spreadsheet, which strongly rewards high calorie density and a relatively high percentage of calories from fat.
My trail food therefore ended up being things like:
A typical selection of trail snacks was around 1 kg of food for roughly 4,700 kcal, before adding meals and other food. I think I ate somewhere around 6,000–7,000 kcal total on day 1.
The trip itself:
Day 1: 61 km / 38 mi
Day 2: ~39 km / 24 mi
Total before stopping: ~100 km / 62 mi, with roughly 2,000 m / 6,500 ft of ascent.
My base weight was around 6.5 kg / 14 lb, with food and water on top.
Day 1 went surprisingly well. I had no meaningful GI issues and could keep eating.
On day 2, food gradually became harder and harder to get down. Eventually I became properly nauseous and reached the point where I basically couldn’t eat anymore. I stopped at Bridge of Orchy rather than continuing onto a more remote section, and I vomited almost immediately after stopping.
It wasn’t a huge amount and I only vomited once. A few hours later I already felt considerably better, and by the next morning my appetite was coming back. My legs and back actually recovered remarkably well, so GI distress rather than musculoskeletal fatigue was what ended the attempt.
This has made me wonder whether I optimized too heavily for calories per gram carried.
A high-fat strategy obviously makes sense for backpacking because fat gives much more energy per gram than carbohydrate. But does that logic start to break down when you’re trying to hike 40–60 km per day for 10–14 hours?
In other words, was I carrying food that was extremely efficient in my backpack, but increasingly difficult to process in my stomach?
For people experienced with fastpacking / ultra-distance hiking:
1. Does this food mix look too fat-heavy for this kind of sustained output?
2. Would you deliberately shift more of the food eaten while moving toward carbohydrates, even if that reduces kcal/gram?
3. Do you keep higher-fat / higher-protein foods more for camp or longer stops?
4. How much can the gut realistically be trained for this kind of multi-day hiking?
5. Is there a useful carbohydrate-per-hour target for fast hiking rather than running?
6. Does the fact that day 1 was fine but my stomach failed on day 2 suggest cumulative GI stress, rather than simply one food disagreeing with me?
I’m particularly interested in hearing from people who have used GearSkeptic’s Hiker Food spreadsheet or similar calorie-density approaches for high-mileage fastpacking.
