Hiking for a month transforms dude's metabolismThe question I had before my thru-hike was this: Would walking all day, every day, for a month improve my metabolic efficiency when I run at a high intensity? In other words, could I become a better athlete by simply walking? Before the trip, I was burning 66 percent fat and 34 percent carbs during low-intensity exercise or any activity during which I had a heart rate of 112 bpm. At a slow long-run pace, with a heart rate of 145 bpm, I was burning 52 percent fat and 48 percent carbohydrates. My crossover point—the heart rate at which I was burning carbs and fat equally—was 153 bpm, or a moderate-to-slow running pace. After the trip, I was, as my test administrator at Real Rehab in Seattle put it, “a fat-burning machine.” At 110 bpm, I was burning 91 percent fat and 9 percent carbohydrates. At 145 bpm, I was burning 70 percent fat and 30 percent carbohydrates. My crossover point had moved to 168 bpm, which I reached at a fairly fast running pace. And even at my maximum heart rate (184 bpm), I was still getting a quarter of my energy from fat. What does this mean? I can now go on long runs without consuming gels and other foods, or at least a significantly reduced amount. Also, the next time I go backpacking, I will be able to carry less weight in my pack because each gram of fat has nine calories, while a gram of carbohydrate or protein provides less than half that energy—around four calories. This means I can carry more high-fat foods like nuts and cheese, while cutting way back on sugary high-carb snacks like energy bars and candy. Plus, if I run low on food near the end of a trip (something that happened several times between resupplies during our thru-hike), my body will be able to run just fine on body fat until I make it to the next rest stop.