In one of my anatomy and physiology books it lists fasting as one of the things that can cause adrenal stress, but unfortunately they don't give any more detail as to how this comes about. Does anyone have any ideas as to why this is the case? Apologies if there is already a thread covering this topic.

Whenever blood sugar drops, your body releases several hormones to increase it again:
Growth hormone
Cortizone (From the Adrenal Cortex)
Adrenalin and relatives (From the Acrenal Medulla)
Glucagon
etc... it's always been notable that several hormones increase blood sugar but only one (insulin) decrease it. Once the blood sugar is normal again, the release stops. This is all part of the "fight or flight" response.

So yes it is true that fasting stimulates the adrenal glands, just like exercise stimulates the muscles. But the physiology book also likely bears in mind that fasting in "normal" situations (like Nature) usually occurs during stressful times, thus it is difficult to say what contribution came from the low blood sugar and what portion is to be blamed on the stress per se.

Please never confuse organ "stress" with organ "damage".. that's why I used the parable of muscles exercising. I fast regularly inter alia to keep the adrenal glands in great fit shape.

André