Leftovers are often a godsend. Too busy on a hectic Monday to put anything worthwhile on the dinner table? Your weekend leftovers are here to the rescue. Hankering for a midnight snack? Last night's leftovers are calling your name.

Stumped for cooking inspiration? Turn those leftovers into a brand-new dish. But, while leftovers can be both convenient and tasty — and some foods are even tastier after a day or two in the fridge — not all leftovers are worth keeping. Or, at the very least, you should think carefully when reheating them.

We're talking leftovers that you shouldn't just sling into the microwave for a few minutes and then eat around the cold spots, like you might be in the habit of doing. To help you keep your belly and taste buds happy, here are some of the foods you should never reheat without a fair degree of caution. Rice Rice is a favorite leftover, whether you've baked it into a cheesy casserole, or you ordered Chinese takeout and now you have an abundance of white or fried rice.

. In fact, this leftover is so iffy that the nasty symptoms that can follow eating it have gained the name "reheated rice syndrome." It's all because rice is one of the handful of starchy foods that can harbor a bacteria known as The bacteria is heat-resistant, so no amount of microwaving or time spent bubbling in a sauce in the oven will kill it, once it forms.

So how does it form and how can you avoid it? The bacteria lives in the rice and is relatively benign at first, but then.