According to the CDC, the average restaurant meal is four times larger than the 1950s. Soda size is 6x larger. Hamburger size more than 3x larger. French fries more than 2x larger.
The average American adult? 26 lbs larger, while only averaging 1 inch taller. (For adult men, the averages went 5 feet 8 inches and 166 lbs to 5 feet 9.5 inches and 195 lbs. For adult women, the averages went from 5 feet 3 inches and 140 lbs to 5 feet 4 inches and 164 lbs. Source.)