You're right that logging and tracking is very hard. It seems cruelly unfair that brain fog is such a factor, since that makes it impossibly hard to figure out what might be wrong, and what to do to fix it. I've tried so hard to find a pattern.
Owing to my fatigue, I must admit that eat a lot of prepared foods. But generally they are the healthy ones- Healthy Choice, Lean Cuisine, etc. Well, as healthy as a box of frozen food can be, anyway.
I do try to get sunlight, but it seems to have a paradoxical negative effect on my now- I feel even sleepier if I take an noon walk.