Re: Dr. Weil skeptical of AF

"Well that's basically what I mean; not having the capacity in producing enough amounts fast enough. "

Well, that's basically not the same thing, :). Capacity refers to size, number, or amount and the ability to hold or produce the desired results. 

The speed at which they (adrenal glands) perform their duties is at best insignificant compared to being able to PERFORM their duties sufficiently. Being able to function trumps how quickly they can function.

I will admit that the problems that arise from low cortisol (and hormones) production can be the result of any malfunction of the elements involved in the HPA axis. 

We know this is possible because secondary adrenal insufficiency causes low cortisol output when the H or P in the HPA axis become impaired. 

As well, the adrenals themselves can under produce which is known as primary adrenal insufficiency. 

So, it is possible for the adrenals to "fatigue" in a sense in the case of primary adrenal insufficiency because they are not producing adequate amounts of hormones, regardless of the mechanism that causes it. 

So why can't they "fatigue" to a point that's not quite considered primary adrenal insufficiency, but is also not adequate for the person to function optimally (ie. without: fatigue, poor digestion, mental fog, food intolerances, cold sensitivities, etc.). This is compounded by the negative feedback loop that exists in the HPA because the hypothalamus produces MORE CRH in response to the low glucocorticoids in the body (this is my understanding of the process), which in turn causes the pituitary to produce ACTH to stimulate the adrenals to secrete more cortisol. But the adrenals can't, which is why the low hormone level exists in the first place. And this brutal cycle continues over and over and over.