Putting the meal in mealworms…

I wouldn’t want to eat stuff like that all the time, but it’s good to have the experience. And heck, that way we know that we can, if we ever needed to!
Yes, I looked up fasting in Liguori’s Moral Theology. And yes, he has a big ol’ chapter on it, in the section on the Precepts of the Church. He had to write extensively about fasting exceptions, because he was living at a time when there were Jansenists with crazy severity, and also a lot of extremely lax Catholics.
So yes, if they can’t reasonably get fasting food or eat their food in a single meal, etc, poor people are totally excused from all the fasting regulations, as they need to be excused! They don’t have to ask anybody’s permission for a dispensation; it’s just an impossibility for them.
And yes, pregnant or nursing women are not only totally excused from fasting, but can actually commit a sin by fasting too much. (The authorities allow as how an exceptionally healthy young lady can maybe fast a tad while pregnant or nursing, but they’re a lot comfier with pregnant ladies being sometimes allowed to eat meat.) Anybody with a sick kid in danger is totally excused from all fasting regs.
And yup, you are automatically excused from fasting if it gives you a headache. (Not from abstaining from meat.) Same thing if fasting keeps you from sleeping at night, which I didn’t know was a thing.
Soldiers are excused from fasting regs if they are living communally with other soldiers who aren’t Catholic, before you even get to them being excused if they are doing hard work, fighting, being on watch, etc. (This is an interesting issue, because of course there were notorious historical/Biblical cases of soldiers fasting and being rewarded in battle, and just as many historical cases of soldiers losing battles in Lent due to weakness from excessive fasting. So it’s a prudence thing.)
Very educational!