I had low cortisol a few years ago and it was all to do with stress. Part of it was life stress in general (I had just finished the schooling for my professional designation which was a lot of stress and work), financial stress, and physical stress.

I had to make sure I eat enough calories for me. I was not doing keto at the time so I can't speak to the WOE and cortisol. I was low carb though. The stress of transitioning from carbs to fat might be a factor but I'm sure someone with much more knowledge than me in that department can chime in.

I was working out 5 days a week, I had to drop that down and stop doing HIIT. I just moved to lifting 3x/week. To this day I have to listen to my body and adjust my workout schedule as required as I know I can backslide again.

I took supplements that helped, adaptogenic herb such as licorice and ashwaganda. I tried to eat balanced, healthy meals. Had to take the focus off weight loss for that time onto weight maintenance.

I hope some of that helps. I'm sorry your dealing with this...low cortisol sucks.

I had low cortisol and suck a few years ago too. It was about a year after I finally figured out my celiac disease and hashimoto's. We were a bit worried about addison's because of my AI history so the doctor had me on some steroids. Those did help but I think I was becoming IR already so that just kind of put it on fast forward for me. I stopped them after a year due to the emergence of prediabetes. I think it was cortef and florinef that I took.

I think there was a slight boost in energy, but it wasn't a lot. Not like with prednisone where you may feel the urge to clean the house at 1am, and you hop to it. LOL

My cortisol levels and such (can't remember the other ones) have seemed to stay pretty steady now, although at the lower end of normal still.

Sleep! After years and years of struggling with low energy, weight that wouldn't come off and high blood pressure my doctor suggested a sleep study. I thought he was crazy and grasping at straws. Just a way for them to make more money off me and more ways for me to be poked and prodded. I slept fine!

How wrong I was ... come to find out my body was waking up around 20 times an hour because I would stop breathing. All night long. That rate increased during REM sleep but I can't remember the number on that. I was given a CPAP machine and within about 6 months I was able to right myself. Weight started slowly coming off and I had energy again. My blood work was much better. Then came keto and things started REALLY going well. I feel like I did when I was 20!

Not saying it's the same for you but you might want to check the possibility out. Sleep apnea is pretty silent unless a partner notices you stop breathing of which mine never did.