Rice hardens in the fridge and flatbread turns leathery, and both are commonly blamed on drying out. Only one of them is actually about water loss.
What staling really is
Starch granules absorb water and swell during cooking, losing their ordered structure. On cooling, the starch molecules gradually reassemble into ordered regions again.
That reassembly squeezes out the water the starch was holding and makes the food firm. It happens fastest at refrigerator temperatures rather than at freezing or room temperature.
Because it is a structural change rather than evaporation, wrapping tightly does not prevent it.
Why reheating works on rice
The reordering is largely reversible with heat and a little moisture, so steaming rice or heating it with a splash of water returns most of the original texture.
Frying it instead takes a different route, driving off moisture and separating the grains so the firmness reads as intentional.
Either approach works because rice is loose grains with a large surface area, so heat and steam reach all of it quickly.
Why flatbread has two problems at once
Flatbread stales through the same starch process, but it also loses water outright, because it is thin and has a large surface relative to its mass.
The gluten network dries and stiffens as this happens, and that part is not undone by warming alone.
Reheating dry bread therefore makes it hotter and harder, which is why the traditional method involves a damp cloth or a brief spell in a covered pan with a little fat.
How storage temperature changes the outcome
Freezing halts the reordering almost completely because the water is immobilised. Bread and cooked rice both keep far better frozen than refrigerated.
Room temperature is slower than the fridge for staling but raises other concerns, particularly for rice, where cooling speed is treated as a food safety matter.
The practical answer for both is to cool quickly and then freeze rather than to refrigerate for several days.
Why some breads keep better than others
Breads made with fat worked into the dough stale more slowly, because the fat interferes with starch molecules reassembling and slows moisture loss.
Layered and fried breads therefore hold up considerably better in a lunchbox than a plain dry-griddled one.
Doughs enriched with yogurt or milk behave similarly, which is one reason those breads became the ones packed for travel.