Hyperpalatable in the context of "HFSS food"

An ultra-processed food (UPF) is a grouping of processed food characterized by relatively involved methods of production. There is no simple definition of UPF, but they are generally understood to be an industrial creation derived from natural food or synthesized from other organic compounds. The resulting products are designed to be highly profitable, convenient, and hyperpalatable, often through food additives such as preservatives, colourings, and flavourings. UPFs have often undergone processes such as moulding/extruding, hydrogenation, or frying.

Ultra-processed foods first became ubiquitous in the 1980s, though the term "ultra-processed food" gained prominence from a 2009 paper by Brazilian researchers as part of the Nova classification system. In the Nova system, UPFs include most bread and other mass-produced baked goods, frozen pizza, instant noodles, flavored yogurt, fruit and milk drinks, diet products, baby food, and most of what is considered junk food. The Nova definition considers ingredients, processing, and how products are marketed; nutritional content is not evaluated. As of 2024, research into the effects of UPFs is rapidly evolving.

Junk food is a term used to describe food that is high in calories from macronutrients such as sugar and fat, and often also high in sodium, making it hyperpalatable, and low in dietary fiber, protein, or micronutrients such as vitamins and minerals. It is also known as high in fat, salt and sugar food (HFSS food). The term junk food is a pejorative dating back to the 1950s.

Precise definitions vary by purpose and over time. Some high-protein foods, like meat prepared with saturated fat, may be considered junk food. Fast food and fast-food restaurants are often equated with junk food, although fast foods cannot be categorically described as junk food. Candy, soft drinks, and highly processed foods such as certain breakfast cereals, are generally included in the junk food category; much of it is ultra-processed food.