“Radiation” might connote images of nuclear plants, but it simply refers to energy that travels in waves and spreads out as it goes. Microwaves, radio waves and the energy waves that we perceive as visual light all are forms of radiation. So, too, are X-rays and gamma rays—which do pose health concerns. But the microwaves used to cook foods are many, many times weaker than X-rays and gamma rays, says Robert Brackett, Ph.D., director of the National Centre for Food Safety and Technology at the Illinois Institute of Technology. And the types of changes that occur in microwaved food as it cooks are “from heat generated inside the food, not the microwaves themselves,” says Brackett. “Microwave cooking is really no different from any other cooking method that applies heat to food.” That said, microwaving in some plastics may leach compounds into your food, so take care to use only microwave-safe containers.