I ate mostly bananas for a week, once. Went into that from basically Atkins. I was surprised to find that it had a very diuretic effect, even though I was trying to eat to maintenance, I kept losing body water. Since I probably went in with low glycogen stores, I would have thought I'd at least gain some glycogen weight.

I wonder if she's checked her blood glucose? Early on, before injecting insulin became an option, a low carb diet was used as an attempt to slow weight loss. Insulin doesn't need to be as high to store 1000 calories as fat and protein as it does to store 1000 calories of carbohydrate, carbs are only fattening if enough insulin shows up to do the job.

Or maybe it's a salt/potassium thing, the usual suggested intakes don't make much difference, but more extreme changes might. I didn't salt those bananas.