The unique Diet jams contain 30 % less calories than regular jam. They are 100% natural and sweetened with fruit sugar fructose. Jam typically contains both the juice and flesh of a fruit or vegetable, although some cook books define it as a cooked and jelled puree. The term jam refers to a product made of whole fruit cut into pieces or crushed, then heated with water and sugar to activate itspectin before being put into containers.