Leftovers can save time, reduce food waste, and make busy days easier. But not every meal is safe to eat the next morning. Food safety experts warn that certain foods can become risky when left at room temperature for too long—even if they still look and smell perfectly normal.

1. Cooked mushrooms and leafy greens: These vegetables can spoil when improperly handled or left unrefrigerated for extended periods. Although claims that all leftover spinach or mushrooms become poisonous overnight are misleading, prompt refrigeration is essential. Divide large portions into shallow containers and keep them cold.

2. Soy products: Fresh tofu and homemade soy milk contain moisture and nutrients that can support bacterial growth. Refrigerate them promptly, use clean utensils, and follow the storage instructions on packaged products. Never assume a cool kitchen is a safe substitute for a refrigerator.

3. Soft-boiled eggs: Eggs with runny yolks may carry a greater risk of harmful bacteria than thoroughly cooked eggs. Cooked eggs and egg-based dishes should be refrigerated promptly, especially when they are intended for children, older adults, or people with weakened immune systems.

4. Seafood: Fish, shrimp, crab, and shellfish are highly perishable. Leaving cooked seafood on the table overnight can allow harmful microorganisms to multiply, and some seafood-related toxins are not destroyed by reheating. When storage conditions are uncertain, discarding it is the safer choice.

5. Cooked rice: Often overlooked, rice can contain spores of Bacillus cereus that survive cooking. If cooked rice sits at room temperature for too long, bacteria can multiply and produce toxins that reheating may not destroy. Cool it quickly, refrigerate it promptly, and avoid eating rice that has been left out overnight.

The most important rule is to refrigerate perishable food within two hours of cooking or serving—or within one hour when temperatures exceed 32°C (90°F). Keep your refrigerator at or below 4°C (40°F), use shallow containers to cool food faster, and reheat leftovers thoroughly. Remember: harmful bacteria do not always change a food’s smell, taste, or appearance. Saving leftovers is sensible, but when food has been left unrefrigerated overnight, it is safer not to risk eating it.