Some strategies to limit sugary drinks may backfire

April 11, 2017, Association for Psychological Science
Credit: S Dusseault/ public domain

In response to policy efforts aimed at limiting individuals' intake of sugary drinks, businesses could enact various strategies that would allow them to comply with the limits while preserving business and consumer choice. New research shows that one of these strategies - offering smaller cup sizes with free refills - can actually increase individual consumption of sugary drinks. The findings are published in Psychological Science, a journal of the Association for Psychological Science.

"Our research provides insight into the effectiveness of a portion limit policy," explains behavioral scientist Leslie John of Harvard Business School, first author on the research. "We identify one circumstance - bundling - where the reduction in purchasing of sugar-sweetened beverages is likely to be realized, and another - refills - where the policy can in certain cases have an unintended consequence of increasing consumption."

The research was prompted by recent policy efforts, such as a 2012 regulation passed by the New York City Board of Health that restricted sold at restaurants and other food outlets to a maximum serving size of 16 ounces. The regulation was ultimately overturned but it generated heated debate about the appropriateness and effectiveness of addressing public health issues through such means. John and colleagues Grant Donnelly (Harvard Business School) and Christina Roberto (University of Pennsylvania) wondered what the real-life effects of such a policy might be.

One way businesses could respond to a portion limit without sacrificing service would be to divide a large drink into two smaller servings, provided together as a bundle. In the first experiment, 623 participants came to the lab and were given an opportunity to buy either a medium or large iced tea or lemonade to drink while they completed other tasks. Importantly, the medium size was always served in one 16-oz cup, but the large was sometimes offered in one 24-oz cup and sometimes bundled as two 12-oz cups.

The results showed that bundling seemed to diminish participants' interest in buying the larger option: People were less likely to buy a large drink when it was bundled than when it was presented as one serving. However, it did not affect the further downstream behavior of consumption.

But what would happen if participants were offered free refills instead of a bundle? In a second experiment, John and colleagues presented drink options to another group of 470 participants. In some cases, the large drink offered was one 24-oz drink, while in other cases it was a 16-oz drink with free refills. Having to get refills did not seem to deter participants: People were just as likely to buy a large single serving as they were a somewhat smaller serving with refills.

Importantly, most of the people who chose to buy the drink with refills did end up getting a refill, and they tended to consume more overall: Participants consumed 44% more calories when they had a drink with refills than when they had a larger single drink.

This may have happened, the researchers surmise, because consumers wanted to get their "money's worth" - that is, they consumed more of the refill since they had already paid for it.

But data from two additional experiments indicate that this unintended increase in consumption can be dampened somewhat by requiring people to get the refills themselves.

"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 write. "However, requiring the participants to stand up and walk a tiny distance to obtain their refills helped to curb it."

The findings underscore the role that contextual cues - such as size perception and social image concerns - play in driving what and how much we consume. Harnessing these cues provides one strategy for promoting healthy behavior that preserves individual choice and minimizes impact on businesses, but more research is needed to understand the unintended consequences such strategies might have, John and colleagues conclude.

Explore further: People buy more soda when offered packs of smaller sizes than if buying single large drink

More information: Leslie K. John et al, Psychologically Informed Implementations of Sugary-Drink Portion Limits, Psychological Science (2017). DOI: 10.1177/0956797617692041

Related Stories

People buy more soda when offered packs of smaller sizes than if buying single large drink

April 10, 2013
People buy larger amounts of soda when purchasing packs of smaller drinks than when offered single servings of different sized drinks, according to research published April 10 in the open access journal PLOS ONE by Brent ...

Free refills from soda fountains no longer on tap in France

January 27, 2017
Offering free refills from self-service soda fountains has been uncommon in France, but now the practice is illegal.

A sugary drinks tax has wider economic as well as health benefits

January 12, 2017
The wider economic benefits of a tax on sugary drinks need to be recognised by policymakers if retailers' pricing behaviour is to be changed, according to a study led by the University of East Anglia (UEA).

Kids' consumption of high-calorie drinks at fast-food restaurants tied to combo meals

October 7, 2016
A new survey of children's and teenagers' eating habits at fast-food restaurants suggests that consumption levels of sugary drinks are closely tied to their automatic inclusion in "combo meal" packages.

Study shows replacing one serving of sugary drink per day by water/unsweetened tea/coffee cuts risk of type 2 diabetes

April 30, 2015
New research published today in Diabetologia (the journal of the European Association for the Study of Diabetes) indicates that for each 5% increase of a person's total energy intake provided by sweet drinks including soft ...

Teens are less likely to select sugary beverages that contain health warning labels

September 8, 2016
Teens are more than 15 percent less likely to say they would purchase soft drinks and other sugary drinks that include health warning labels, according to a new study led by researchers at the Center for Health Incentives ...

Recommended for you

Moderate exercise before conception resulted in lower body weight, increased insulin sensitivity of offspring

October 22, 2018
Men who want to have children in the near future should consider hitting the gym.

Juul e-cigarettes pose addiction risk for young users, study finds

October 19, 2018
Teens and young adults who use Juul brand e-cigarettes are failing to recognize the product's addictive potential, despite using it more often than their peers who smoke conventional cigarettes, according to a new study by ...

Self-lubricating latex could boost condom use: study

October 17, 2018
A perpetually unctuous, self-lubricating latex developed by a team of scientists in Boston could boost the use of condoms, they reported Wednesday in the journal Royal Society Open Science.

Engineered enzyme eliminates nicotine addiction in preclinical tests

October 17, 2018
Scientists at Scripps Research have successfully tested a potential new smoking-cessation treatment in rodents.

Nutrition has a greater impact on bone strength than exercise

October 17, 2018
One question that scientists and fitness experts alike would love to answer is whether exercise or nutrition has a bigger positive impact on bone strength.

How healthy will we be in 2040?

October 17, 2018
A new scientific study of forecasts and alternative scenarios for life expectancy and major causes of death in 2040 shows all countries are likely to experience at least a slight increase in lifespans. In contrast, one scenario ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.