I take a supplement with zinc (7mng), magnesium (130mg) and calcium (400mg), and just eyeball on a teaspoon some “lite salt” (sodium and potassium) 6 times a day. I wasn’t feeling nearly as well on just lite salt. When I first took magnesium and calcium it was a higher dose (I think 3~4x as much?) and I felt a bit sick (maybe too much for empty stomach?), but lowering the dose made me feel better, so don’t necessarily increase the quantities if you aren’t feeling well.
When I was doing 1~2 weeks fasting I was open to cheating a bit. I would generally have a bit of mustard, sriracha, cayenne pepper or eat a black peppercorn, but every now and then I would even eat a whole tomato with some salt and black pepper. Autophagy isn’t an on and off switch, and those 20 calories a day really feels like too much margin of error to really matter.
This possibly doesn’t help everyone, there probably are people where this would just make them hungrier, but when fasting I just start to really miss the taste of things and this really helped. Before doing that I would usually just get to a point where I became too unproductive and drop my fast frustrated.