One of my kids especially has a major love of popsicles

obvious sugar concern there.
when they're not there, she doesn't have a big problem with it.
I think what I am going to start doing is only have X many available in a week. When they are gone, they are gone.
Maybe you could do the same thing with the protein bars, since you mentioned they're expensive? It still allows you to control your budget, but *not* her eating...
though I do get the concern with eating a bunch of chocolate covered protein bars in one sitting.
I have known people who have taken that approach though and the kids tend to get over their fascination with the particular food pretty quickly once they're given this level of control, and then have to live with the consequence of not having any more for a few days.
also with other sweets. (I do limit ice cream to once a day when we have it, but also I only buy at one particular store where 'decent' ice cream is inexpensive, or when there's a sale at same price somewhere else I happen to be, so it's limited by that as well, for one example.)