Exactly .... "Your body burns fat and carbohydrates to produce energy. Carbohydrates are stored in the form of glycogen in your liver and muscles and glucose in your bloodstream."
James has hit a fundemental point that makes what should actually be called "the carbohydrate drip method" even more important.
In weightlifting circles it's widely discussed that once you use up the glycogen stores in your muscles you begin to burn muscle along with the glycogen in your liver. Once you've depleted your glycogen store in your liver, your burning mainly muscle until your body can process stored fat for energy.
So ... when you "hit the wall" and push beyond that, you've actually pushed your body to begin to feed on muscle tissue because it's a more easily burned fuel than fat, in the absence of glycogen. That glycogen storehouse is critical for utilizing fat instead of muscle as energy .... as such, taking in carbs to burn as energy, and sparing the glycogen stores, allows your body to metobolize fat for excess energy instead of protein stored as muscle tissue.
You should be taking eating the correct ratio of nutrients during the day as well .... take a multivitamin if necessary, but your body needs these substances to perform it's functions properly.
The ratio of sources of your food intake is critical per the timing of your exercise also, as James talked about in his post. Consuming fat during exercise doesn't have a great energy benefit. Consuming some type of easy to digest protein is important to support your muscle regeneration after exercise, but carbs are your best source of energy during exercise.
As such, I aim for a caloric intake of at least 50/30/20 for my diet .... or, 50% carbs, 30 % fats, and 20% protein.
My carbs are taken stretched out during the entire day, many to support my glycogen stores and some for increasing my metobolic rate at bedtime to generate heat. The bulk of my protein intake is taken at dinner, and the bulk of my fat intake is taken in the afternoon and before bed. That way, the fat is metabolizing slowly when it can be stored if necessary, the carbs are supporting glycogen and immediate energy needs, and the Protien is helping to rebuild muscle tissue from sustained hard exercise.
Water and salt are critical parts of the equation. without them, the body stops functioning properly if at all.
Lastly ... you can operate at a caloric deficit over time, or take in fewer calories than you are burning without feeling hungry, only if you pay attention to the timing of what you eat. That timing is the key to hiking with less food and utilizing your natural storehouse of fat as energy, which, by the way, you are forced to carry anyway.
If you'd like proof, then go out an buy 6 snickers bars and consume them over the course of a 8 hour day hike, along with water. Don't have breakfast and eat a regular dinner when you get off the trail.
The following week, buy 6 Balance Gold or Clif bars and consume them over the same day hike, along with water as well as a carbo drink such as Gatorade or Poweraid. Same deal, don't have breakfast and eat your regular dinner when you get off the trail.
Same gear, same shoes, same pack, same equipment, same weather conditions .... try to limit your varibles as best you can to just the food.
You'll be amazed.