We've all heard of processed foods, but what about ultraprocessed foods, which make up more than half of the typical American diet? In this special Chasing Life: Spotlight, CNN Medical Correspondent Meg Tirrell explores how these foods became so widespread and the potential risks they pose to our health. She speaks with Professor Marion Nestle, a leading authority on nutrition and food policy and NIH senior investigator Kevin Hall, who conducted the first and only controlled clinical trial on ultraprocessed foods. Hear about the study's remarkable findings; it may change some of the choices you make in the grocery store.    Learn more about your ad choices. Visit podcastchoices.com/adchoices