Individuals who are 'natural' (not using performance-enhancing drugs) are more susceptible to significant hormone suppression and nutrient deprivation if they engage in extreme calorie restriction or excessive cardio.

“because as a natural you are very susceptible to Major aberration and hormone suppression if you are going to deprive the hell out of nutrients and especially if you're doing huge amounts of cardio concurrently because you think that's what you need to be doing”