Junk Food Day is devoted to junk food, which is food mostly devoid of nutritional value, but instead is high in fat, sugar, and salt, and often highly processed. When eaten in high amounts, junk food may impact energy levels, contribute to obesity and cardiovascular disease, and advance other health problems. It may even alter brain activity and affect emotional well-being.

The word “junk food” is usually thought to date back to the early 1950s, although some have credited Michael F. Jacobson of the Center for Science in Public Interest as coining the term in 1972. The list of foods that are considered junk foods is endless. Most foods at fast food restaurants are considered junk foods, although not all offerings are.