When we exercise, we use carbohydrate and fat as fuels to power us. Sometimes marathoner's "bonk" around the 20 mile mark. Bonking refers to the idea that your body has used up all of the glycogen stores and you have to stop running because you have no perceivable energy left to continue. If we train ourselves to burn more fat and less carbohydrates when we train, we won't bonk because the amount of energy we store as fat is way less limited than the amount of energy we have stored from glycogen. I'd imagine this is definitely important for those ultra long distance races, like ultra runs that can be 100 miles long.
Maffetone teaches us that we can increase our aerobic capacity by training at heart rates in an aerobic range of 65-85% of the maximum heart rate. By training in this range, we train our body's to be more adapt at burning fat while burning less glycogen.
The ketogenic advocates argue that their bodies will become more adapt at burning fats if more fats are consumed while decreasing the carbohydrate consumption. Unfortunately, they usually talk eating lots more animal fats and protein while limiting carbohydrates. I'm wondering if anyone has tried to remain on a starch based diet while decreasing the starch and increasing the fat intake (like more nuts, seeds, and avocado etc......but no oil). I'm thinking like suppose your breakdown is 80% carbs, 10% fat, and 10% protein and then you try something like 60% carbs, 30% fat and 10% protein. I know that fat you eat is the fat you wear, but the idea here is to use that fat that you wear as an energy source for ultra endurance athletes.
These thoughts occured after reading
https://idmprogram.com/fasting-and-exercise-fasting-23/