The Kaltman family tries to sell as much butter as possible at their New York dairy store in 1943 before a government deadline to freeze sales. During World War II, the federal government rationed butter in an attempt to control supply and demand while manufacturing plants were being used to support the war effort. As a result, margarine, which contains trans fat, grew in popularity.
In 1957, the American Heart Association started encouraging people to limit fat in their diets in an effort to lower the risk of heart disease.
As the popularity of fast-food restaurants grew, so did Americans' consumption of fat, calories and salt. In 1984, advocacy groups started campaigning to get saturated fat removed from fast-food chains. As a result, more restaurants began using partially hydrogenated oils that contained trans fat.