This study seems to have been done by someone who doesn't understand what food insecurity is.

Food insecurity is causation; unpredictability is just a bonus trauma for those who already have food insecurity.

Edited to add: food insecurity to also include not having meals that can be eaten comfortably, or lack consistency of the quality, texture or autonomy of having choices in the food being eaten.

Being forced or coerced to eat food that is repulsive or being forced to eat when not hungry/being denied food when hungry is all part of food insecurity.

It's one thing to have access to food, it's another to have access to food that one can actually not be miserable eating.