Due to two-career families, increased affluence, outside activities, and a faster paced lifestyle, fast food has become an integral part of life in some industrialized countries. Fast food eateries are more often frequented by people on their own or non-related groups than by families, thus the importance of sharing a meal and mealtime together is being lost, a not so insignificant factor in family breakdown. Fast food is also typically low in freshness and flavour, high in fat, cholesterol, sugar and empty calories which contribute to heart diseases, dental disease and obesity, although there is increasing appearance of "healthier fast food".
In 1984, the USA had a $47 billion fast-food market, which has been further expanded with the introduction of microwave fast-foods being sold in supermarkets' freezer, mobile fast-food vans cruising busy areas at lunchtimes, and home delivery services. The fast food market in the UK in 1986 represented £1,675 million.
A child's soft drink in the late 1950s was 240 ml; in 2000 it was 355 ml, and a "large" soda 1,024 ml and 310 calories. In 1992, McDonald's introduced Super Size Fries, containing 25 grams of fat and 540 calories (research shows our bodies can only process about 800 calories at any one meal before excess calories are stored as fat).
Junk food is short on fibre, which is known to help keep cholesterol levels down, as well as potent antioxidants abundant in fruits and vegetables, which may offer some protection against heart disease, cancer, and other chronic illnesses. Blood tests of people who principally eat junk food tend to have lower than average levels of folate, vitamins B-12, C, E, and A, as well as beta-carotene and other antioxidants.