Now this surprised me......
"The term junk food dates back at least to the early 1950s, although its coinage has been credited to Michael F. Jacobson of the Center for Science in the Public Interest, in 1972. In 1952, it appeared in the Lima, Ohio, News, "'Junk Foods' Cause Serious Malnutrition", the headline for a reprint of a 1948 article from the Ogden, Utah, Standard-Examiner, originally titled, "Dr. Brady’s Health Column: More Junk Than Food".
And some useful definitions:
"In Andrew F. Smith's Encyclopedia of Junk Food and Fast Food, junk food is defined as "those commercial products, including candy, bakery goods, ice cream, salty snacks, and soft drinks, which have little or no nutritional value but do have plenty of calories, salt, and fats. While not all fast foods are junk foods, most are. Fast foods are ready-to-eat foods served promptly after ordering. Some fast foods are high in calories and low in nutritional value, while other fast foods, such as salads, may be low in calories and high in nutritional value."
Junk food provides empty calories, supplying little or none of the protein, vitamins, or minerals required for a nutritious diet. Many foods, such as hamburgers, pizza, and tacos, can be considered either healthy or junk food, depending on their ingredients and preparation methods.[18] The more highly processed items usually fall under the junk food category, including breakfast cereals that are mostly sugar or high fructose corn syrup and white flour or milled corn.
The UK's Advertising Standards Authority (ASA), which regulates the UK ad industry, uses nutrient profiling to define junk food. Foods are scored for "A" nutrients (energy, saturated fat, total sugar and sodium) and "C" nutrients (fruit, vegetables and nut content, fiber and protein). The difference between A and C scores determines whether a food or beverage is categorized as HFSS (high in fat, salt and sugar; a term synonymous with junk food)."
https://en.wikipedia.org/wiki/Junk_food