Tweaking Food Delivery Apps Can Lower Calories Purchased

Becky McCall

May 24, 2023

DUBLIN — Changing the way food options and information is presented on food delivery apps, as well as default smaller portions, may encourage healthier selections, lowering the calorie intake by 4%-15%, show three new randomized trials from the UK.

The prominent positioning of low-calorie menu items, and restaurants with low-calorie main meals, on a food app emerged as the most promising approach to promote healthier eating, followed by preselecting smaller portions by default, and finally calorie labels, reported Anna Keleher, MPA, a behavioral scientist at Nesta, London, UK, here at the European Congress on Obesity (ECO) meeting.

"Many out-of-home meals have more calories than meals cooked in-home and using delivery apps is linked with a higher risk of becoming overweight or obese," she remarked. "We're interested in understanding more about delivery apps because they can be modified at scale easily and can reach millions of people with interventions to promote healthier and more nutritious options in these settings."

Food delivery apps have surged in use in the UK with a 55% increase since 2015; examples include Uber Eats, Just Eat, and Deliveroo. "This trend is similar in the US, with more and more consumers using delivery apps to buy food," said Keleher, who is also a senior advisor at the Behavioral Insights Team in New York. 

Emma Boyland, PhD, an obesity psychologist from Liverpool University, UK, said: "Apps are an increasingly popular way for people to buy food and the virtual food environment is becoming as prominent as the physical food environment in how we go about obtaining meals."

She highlighted the need to understand more about how food apps change the way we purchase and eat, but noted that "the work presented today" showed that "moving the position of food choices and information, as well as the brand name and imagery, influences what people end up buying and consuming."

"I think there's a place for interventions that challenge these things and improve dietary health," continued Boyland, who chaired the session during which Keleher presented her results. "However, as we've seen with calorie labeling, they don't always have the biggest effect on their own, so as is often the case, we need to take multiple actions, incorporating all the elements of the environment to make a meaningful difference."

Three Trials Changing Displays on Simulated Food Delivery Apps

"Delivery apps could reach millions of people and help us select healthier food options, and yet there is very little research looking at what works to promote healthier and more nutritious options in these settings," said Filippo Bianchi, MD, a colleague working with Keleher in a press release issued by ECO.

So the research team carried out a proof-of-concept testing of health-promoting interventions by developing a simulated food delivery app and asking 23,783 adults who typically use such services to choose a meal for themselves as if it were a real-life food delivery order.

"As a first step, we developed a simulated online food delivery platform to generate evidence on the effectiveness of our interventions," Keleher explained, noting that the simulated platform included 21 restaurants and almost 600 food and drink items to choose from.

The research evaluated 14 interventions across three randomized controlled trials, displaying various food-ordering options that promoted lower-calorie options against a control. The trials investigated default choices (promoting the selection of small portion sizes through defaults, n = 6000); positioning (promoting the selection of less calorie-dense options through positioning, n = 9003); and labeling (promoting the selection of less calorific options through calorie labels, n = 8780).

The primary outcome was the total number of calories in the basket at checkout. The results were adjusted for potentially confounding factors, such as BMI, age, gender, and income.

For the trial that promoted smaller portions by default, "all of our interventions significantly reduced calorie purchases, with each additional intervention element increasing the effect sizes, which ranged from a 6% to 13% reduction in calories [–5.5% to –12.5% kcal/order; P < .05]," reported Keleher.

The second trial varied the position of both items on the menu and the order of restaurants — effectively, lower-calorie menu options were more prominent, and restaurant options with lower-calorie main meals were placed at the top of the restaurant selection page.

Keleher noted that there have been some concerns about whether this strategy would negatively affect restaurant business, so they counteracted this by also incorporating an option where low-calorie but high-price options were placed near the top of the display to promote healthier options but without loss of income for participating restaurants. 

This last intervention with low-calorie/high-price options placed near the top also led to reduced calorie intake.

"This showed that promoting low-calorie options does not necessarily mean damaging business revenue," she said. "We hope that the industry can evolve to meet the widely recognized needs of society and consumers."

Repositioning restaurants emerged as more effective than repositioning foods on the menu, while all interventions significantly reduced calorie purchases. "Effect sizes ranged from 6%-15% reductions in calories purchased per order [P < .05]," reported Keleher.

The last trial tested seven calorie labels, including four that changed the font size and location of the label, two added a switch on/off filter for calorie label display, and the last was a calorie summary at checkout.

"All these standard calorie labels directionally reduced the number of excess calories with two [options] reaching statistical significance. Five out of seven labels significantly reduced calorie purchases with effect sizes ranging from 4.3% to –7.8% kcal/order (P < .05)," reported Keleher.

"This research is important for policymakers so they can understand the best way for companies to display calorie labels and what to include in regulations and guidelines," she summarized.

Qualitative Think-Aloud Study Explored Views Around Food Delivery Apps

Another piece of research, the Think-aloud study, by the same authors, was also presented at ECO, and explored how best to enhance the effectiveness and acceptability of calorie labels in food delivery apps in consultation with 20 adult delivery app users in the UK.

Researchers tried to document the range of views people have about calorie labels, including variation both between people and within an individual.

"For example, on a weekend, people might not want to engage with calories at all because they are more concerned to treat themselves, whereas at a mid-week lunch that same person might really want the ability to check the calorie content of their food," Keleher reported.

She also said that considerations varied significantly between people such that they described different ways in which calorie labeling impacted their food-ordering experience.

"Some people felt labels supported their existing intentions, whereas others felt labels built their knowledge. Still others felt calorie labels were insufficient to support their health and wanted more information, such as on macronutrients," said Keleher, quoting one participant: "There's no situation in which I would look at [calories]. I look at nutrients. I prefer the traffic light system [color-coding salt, fat, and sugar content]," she relayed.   

The key recommendations based on the Think-aloud study included: providing a filter that allows users to switch calorie labels on and off; communicating recommended energy intake per meal (ie, 600 kcal) and not just per day (ie, 2000 kcal); and avoiding framing calorie label messaging or formatting as judgmental (eg, red fonts).

"These studies provide encouraging proof-of-concept evidence that small tweaks in delivery apps could help many people to identify and select healthier foods. Testing similar initiatives with real restaurants and delivery apps will be important to assess the long-term impact of these interventions in the real world. Further research should also explore the best way to balance desired health impacts while minimizing effects on businesses and on cost-of-living concerns for consumers," concluded Bianchi.

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