Do you know how a microwave oven works? Do you know when it is safe to use and when it is dangerous? You could look it all up on the interweb, but you don’t have to – because we’ve done it for you.


Microwave ovens use radio waves at a specifically set frequency to agitate (make vibrate) the water molecules in food. As these water molecules get increasingly agitated they begin to vibrate at the atomic level and generate heat. This heat is what actually cooks food in the oven.
Microwave ovens can be a godsend for busy parents or exhausted professionals. Last night’s meal can be reheated – or a new one prepared within minutes.

Because of the uneven moisture content of food, some foods can cook unevenly. That’s why you may have a cold spot in the middle of your reheated lasagna and why microwave instructions often say “stir once and then heat for an additional x minutes.”

A new-mommy trick is to microwave a dry baby blanket before swaddling the baby. The moisture that is in the air, is also in the baby blanket. It is there in small amounts – just enough to warm the blanket to a comfortable level. Heat for 30 seconds or one minute and test it on yourself first.

There are some items however, which should NEVER be microwaved.

  • Eggs. Remember the part about vibrating molecules generating heat? In any moist food this will result in steam. In an egg, trapped in an eggshell, the steam has nowhere to slowly escape to and so the result is a terrific eggs-plosion. If you would like to use your microwave to hard boil an egg, take the eggs OUT of the shell first.
  • Paper bags. If you are a popcorn lover, you may have tried to DIY in a paper bag instead of buying the chemical-laden microwave popcorn bags. The issue with this is that the paper bag also has glue and ink on it which can emit toxic fumes.  In addition, your bag could catch on fire. Don’t do it. The stovetop is the safest place to pop your popcorn – or in an air popper.
  • Fruit. Why would you want to microwave fruit? We aren’t sure why you would, but if this thought occurs to you, don’t do it. The skin on the fruit acts like the eggshell on the egg. Your fruit is likely to explode due to its high water content. If you want to microwave fruit – for a recipe or something - slice it up first.
  • Frozen meat or poultry. Remember that cold spot? This is more likely to happen with your frozen chicken breast than it is with your leftover lasagna. In addition, according to the USDA, microwaving to thaw meat, can cause some areas of the meat to get warm and spur the growth of bacteria, which could cause the meat to spoil if you let it sit around for a while before cooking it.
  • Food wrapped in plastic. You can store those leftovers in plastic, but remove them before heating them up in the microwave. There are a host of issues with plastic in the microwave. It can melt onto your food. Plastic contains endocrine-disrupting chemicals like BPA and BPS that can leach into food. Did you know that 95% of 400 plastic food containers tested, including those labeled as BPA-free, released toxins when the containers were subjected to heat from a microwave, dishwasher, or even hot water? Instead of plastic – heat or reheat food in glass or microwave-safe ceramic plates. Cover items with paper towels, or a paper plate, if you need to cover anything to prevent splattering.
  • Oil. If you’re trying to save food prep time by heating oil in the microwave – stop. Because oil is virtually water-free, it doesn’t get hot. In contrast, butter is about 16% water which is why you can nuke it (in a glass container) and get melted butter very easily.
  • Foil. If you’ve done this by accident, you know that tin foil wrapped food will spark. It can also cause a fire which is not a desired reaction when making dinner. When you’re reheating leftovers, always take the foil off first.
  • Nothing. Don’t turn on your microwave unless something is inside of it – unless you’d like to replace it and buy a new microwave. The oven will be attempting to heat something (but nothing is there) which can cause the oven to overheat and shut down. When your microwave is empty, there’s nothing to absorb those waves, and a disaster awaits.
If you avoid these few items, microwaving your food should be perfectly safe.


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