Size Really Does Matter at Mealtime

Could packaging be responsible for those extra five pounds?

By PT Staff, published May 1, 1997 - last reviewed on June 9, 2016

It's not just the size of our appetite that determines how much cereal we pour into our breakfast bowl. According to University of Illinois researcher Brian Wansink, Ph.D., people tend to take more food from big packages than than they do from small ones.

For example, in one experiment Wansink asked 98 mothers in New England to show him how much spaghetti they would cook when making dinner for two. When he gave participants a small package of pasta for the demonstration, they took an average of 234 spaghetti strands. But women given a package twice as large removed 302 strands--a 29 percent increase. Similar results occurred when Wansink substituted various-sized packages of vegetable oil or M&Ms candy.

The trend does peter out as jars, cans, and boxes assume titanic proportions. But why does package size affect how much we eat in the first place? It's mostly a matter of money, says Wansink. In this age of wholesale clubs like Costco, people are well aware that bigger packages equal lower prices--so they heap on a little extra. Exhibit A: When Wansink offered study participants bottled water, they filled their glasses higher if the liquid was served in a large pitcher. But when he repeated the test using something that's basically free--tap water--the container size didn't matter.