Hi all.  I just started ADF almost a week ago and have a quick question about how much the weight loss from this plan is due to the body going into starvation mode vs just from an overall caloric deficit.  I'm doing 36/12, although on my eating days I basically hold off until I really need to eat, so it's been closer to 40/8.  Basic history is that I started at around 182 lbs, hoping to lose 1.5-2 lbs per week for 30 days (after which I'll reassess).  

Each of my first three fasting days I've had issues with headaches, especially at night.  I searched some old posts in the subreddit so I'm trying to hydrate well (sometimes adding a pinch of salt) and I'm trying to be consistent with just one morning coffee daily.  Last night it was pretty bad and I was having trouble sleeping, so at around 1am I had a tiny snack of a one-spoon bite that included chicken breast, corn pudding, and a smear of mayo.  Couldn't have been more than 75 calories.  Also it was fucking delicious.  After about 10 minutes my headache was gone and I was able to fall asleep easily.

So, I know that studies show 500 calories on fasting days shouldn't affect things too much.  I also know that some people think this is unlikely to really be the case.  Just wanted to get some thoughts on whether or not I'm going to really affect my progress with a small pre-bed snack on fasting days (again, around 75 calories, no sweets or anything like that).  In terms of calories it won't make or break anything, but what I don't quite understand is how much (if any) it should affect my body choosing to burn only fat after a certain amount of fasting.  I want to keep myself sane and happy so I can make the 30 days, but also it's just 30 days so if I need to tough it out I can do that too.  Hopefully that makes sense.  Thanks!