The New York City Board of Health's recent attempt to pass a regulation that says sugary drinks sold at restaurants can’t be more than 16 oz spurred a lot of discussion among public health experts over how business would possibly react to such stricter rules. One suggestion was that stores could start offering a “bundle” option; say you order the extra-large soda, but they just give it you in two 16-oz cups—problem solved.
To test the idea, researchers recently published a study in the journal Psychological Science that investigated that possible response to the proposed NYC policy. They set up a lab experiment with over 600 people that gave them a choice of a medium or large lemonade or iced tea while they did some other sneaky psychologist busy work. The medium was always served in a single 16-oz cup, while the large either came in one 24-oz cup or two 12-oz cups at the same time. Ultimately, they found that the bundling option made people less likely to go for the large portion.
But the researchers set up a second experiment in which they tossed out the bundling idea and gave the customers a choice of a 24-oz drink or a 16-ouncer with free refills. People didn’t seem to mind the extra work to get up and walk to get refills, and chose that selection about the same amount as the bigger drink. They did find, however, that those who got the refill option (brought by a waiter) ended up consuming 44% more calories. When the subjects had to walk a “few steps,” the study noted, they didn’t drink as much.
"Taken together, these results suggest that this method of complying with a sugary-drink portion limit could have the perverse effect of increasing consumption," the researchers said in the study. "However, requiring the participants to stand up and walk a tiny distance to obtain their refills helped to curb it."