Ketosis sounds Scientific and strange but its really easy to understand .
Burning FAT.
http://lowcarbdiets.about.com/od/faq/f/whatisketosis.htm
In order to become an efficient performance engine , you need to train your body to burn fat.
There are a few ways to approach this.
1. DIET
2. FASTING
3. EXERCISE
With diet, an individual needs to start shifting foods to high fat content. This adapts the Gall Bladder to learn how to process these foods. This is similar to the famous Atkins approach.
With Fasting, you restrict the calories and the frequency of meals. This approach is difficult but adapts the body to process onboard fuel/fat but exhausting the sugars first is essential to success of this method.
The last approach is through exercise. Using careful understanding of Lactate Thresholds , you can maximize the training zones for your heart rate so that burning fat is maximizes and sugar is preserved or not burned as quickly.