Fatty Fortitude

Is Fat really the best fuel for endurance?

The latest Atkins diet, the Primal diet, the 4 hour body, all of these contend that fat is the fuel that we should choose.

This does make sense in a few ways:

1. We store seemingly unconstrained amounts of energy as fat. 
2. Our bodies take sugars and make them into fat really quickly
3. Our bodies tend to metabolize more fat for energy during activities of moderate intensity

But what about the 'carbing up' activities of countless, and skinny (read : fat free) marathoners. Can people really be burning fat as fuel when trouncing out a 7 minute mile?

Without knowing the rough biochemical pathway they each of these substances has to travel to ultimately end up as ATP (adenosine triphosphate - the fuel that is ultimately employed by muscles to contract) we are a bit in the dark. I will be addressing this in some future posts so that we might be able to tell if using fat is good for endurance, or if its good for everyone.