My symptoms are similar to your mother's. as we age we lose dopamine producing neurons, if we lived long enough theoretically everyone would lose enough of these neurons resulting in the manifestation of some parkinson's symptoms. pd'ers have lost a lot more of these neurons and have to get dopamine from oral medication which works well but gradually works less well as the natural dopamine production in the brain decreases to the point where you have to take dopamine many times a day in the form of l-dopa. your brain doesn't need a lot of l-dopa and it's estimated less than 5% of the l-dopa you take actually gets to the part of the brain where needed. this is due to the fact that every cell in your body has enzymes in it that destroy l-dopa, which is good if you don't have pd, you really don't want l-dopa getting into your brain if your're healthy, it can lower your blood pressure, cause mental problems. but pd'ers need to get l-dopa thru the stomach, thru the small intestine, into the blood and eventually into the brain, all the while running a gauntlet of cells that destroy it. so the goal of every pd'er taking l-dopa (the active ingredient in rytary) is to get l-dopa into the brain as fast as possible BUT NOT TOO MUCH l-dopa. and that's the challenge. too much rtytary causes involuntary movements, too little causes the rigidity and fatigue. so, what slows down the movement of l-dopa to the brain? well, anything that slows down the movement of food thru the digestive system. gastric emptying takes longer with fatty meals, i assume the same with fiber. protein interferes with l-dopa getting to the brain. constipation, changes in bacteria can have an affect. now i'm describing my situation, i can't say with 100% certainty that your mother is in the same boat. if i ate a slice of pizza i would have to wait at least 2hrs before my next dose, if i ate half a pizza it could be much longer. so food for me is the primary thing i have to control if i don't want long off times.
to solve this problem, i should figure out a diet that would have minimal negative affect on my pd until the evening where i could eat the majority of my protein since i could afford to be off. so that means eating small meals with less than 4grams of protein/meal. unfortunately i don't have the will power to do this everyday and knowingly eat too much at just go OFF and wait 2hrs for my next dose, sometimes i'll take extra l-dopa sooner than 2hrs, maybe 250mg instead of 150 but one has to be very careful.
so unfortunately i can't give you a meal planner to try to see if your mother's inconsistency is caused by food, the simplest thing to do is have her skip a meal or fast for half a day and see if the rytary does a more consistant job controlling her pd symptoms. if it does, then at least you know looking into creating a diet for her is worth the effort.. it's hard to believe but you won't find many meal planners with recipes for advanced pd'ers even though food can have such a major affect for some pd'ers. if her neuro will talk to you ask him/her about this.