@Clerner : When I get adrenal symptoms from fasting or under-eating, it tends to be light-headedness and fatigue, little bit of thready heartbeat, stuff like that. IMO headaches are probably detox or maybe blood sugar. My feeling is that most headaches caused by fasting are detox related, because they go away with time, but YMMV.
That said, if your adrenals are really in the toilet, even a single overnight fast might be too much.
I stopped fasting so much because eventually it did seem to be giving my adrenals a hard time, and then my thyroid a bit. I like fasting so plan to go back to it more gently (no more than two days a week) after the first of the year sometime. Every other day or three days per week is too much for someone like me (and probably you) to sustain long-term. Maybe for anyone to sustain.
But in the interim I found another strategy that has helped me lose weight quickly if not painlessly: very high carb/very low fat. It's an old strategy that's fallen out of favor, but a friend thankfully put me onto it right around Thanksgiving, and after reading about what it did for insulin sensitivity in the majority of folks (insulin sensitivity is of primary importance to me since I am hyperglycemic), I decided to try it. Damned if it didn't work, and fast, too.
The book I got about it is called "The Rice Diet". It's on Amazon. You can also Google it. The book is not entirely satisfactory in that it's what I call a 20th-century self-help book: short on science and kind of long on fruity anecdotes. But it gives a thorough run-down of how to do it. It's pretty simple.
I tried Pritikin back in the day, hated it, but I didn't have a spine then, either.
Plus I think I'm tolerating the Rice Diet better than Pritikin becuase it's a little different in that it emphasizes starches not veggies. It's also different that in the weight loss phase of it you're not supposed to use any animal protein except a little milk, and fish once per week. I think it may be easier than what I remember of Pritikin because of the emphasis on starches.
Anyway, the Rice Diet has been around for quite a long time (since the '50's), and anecdotally it can be used for a long time, even for morbidly obese people to reach their weightloss goals. But I see it as more of a shorter-term intervention. It can be easy to under-eat while on it, and although I've only been doing it since Thanksgiving I had to break with it twice already to get my calories up a couple days per week because I was getting adrenal and thyroid symptoms like when I was fasting too much, pushing my body too hard. But I exercise quite a bit now (at least an hour per day) so that may have something to do with it.
So, if you want to try "ricing", my experience with it has been very positive. It's called the "Rice Diet" but it's not all rice, and I've lost about 12lbs in a little over two weeks. I know it's not all water, too. My loss stalled a bit because of my last break over this past weekend, but I plan on not being anal-retentive with it until after the first of the year when the holidays are over. I have a big wedding to go to in March so I'm hoping to reach my goal by then, otherwise I wouldn't be in such a hurry.
Keep in mind that ricing can be kind of an extreme diet change, though, and the first week can be troublesome with cravings and headaches (detox symptoms), etc. Starches with no fat and no salt can be unsatisfying. You're not hungry, but your mouth just wants to chew other food, if that makes sense. Maybe suck on a stick of butter.
Etc.
Also to keep in mind that if you choose to try the Rice Diet and are having acute adrenal symptoms, the very low salt component of the diet may not be the thing for you. You need that salt. But you can salt your food and still do very low fat, which IMO is the biggest key to the success of this, anyway.
Do you have blood sugar problems...?