Almost every jar of pickles claims a serving of pickles has zero calories. Now clearly, this is incorrect and the result of exploiting some ridiculous FDA loophole, since anyone knows that cucumbers provide calories.
So let's say you're in a situation where you lose all access to food, but you've got effectively unlimited access to pickles -- like, you're trapped inside a recently abandoned pickle warehouse.
Could you conceivably eat enough pickles to survive for a month? Two months? Or would your body just shut down from all the sodium and acid?
It would take more energy to digest the pickle than the pickle would provide.
One example that I like to use is this: would a cockroach eat it? Roaches eat everything from food crumbs to wallpaper paste. Anything with calories. Do you know something that roaches WON'T eat? Cucumbers.
So long as the pickles don't have sugar in the brine, I would say you would likely starve to death.
Nature has a way of providing an observable metric.
Let me correct my statement. Given no alternatives, cockroaches will eat anything without a caloric deficit. Hence my statement about wallpaper paste. A true infestation of cockraoches will eat anything that will sustain the intrusion. If there is no available "food" around, cockroaches will crawl over cucumbers to eat the paste holding the wallpaper to the wall.
So long as there is no additional sugar in the brine (hence calories), the roaches will not eat the pickles.