Originally Posted by RunbikeSki
HC, yeah, I know what you mean. But, she is very small, so over all intake is pretty low to begin with and she leans towards a lot of eggs and whey powder shakes (too many IMO - but I'm not her). I've seen her equivalent to FD and I don't really know how she does it... but she does.
It might be that her protein intake is high enough that the extra being converted to carbs is enough for her.
Someone that small will burn fewer calories per mile.
Also effort level is a factor-running at 65% of MHR will use a higher percentage of fat for energy that running tempo at 85% so fewer carbs are needed to fuel endurance training.