Helping people choose lower-calorie options when ordering takeaways in food delivery apps could help tackle obesity, three new studies suggest.
Data presented at the European Congress on Obesity in Dublin, Ireland, suggests that displaying healthier foods and restaurants more prominently – and/or making small portions the default option – helps people choose more wisely.
Such measures, together with showing calorie labels, reduced the total calorie content of takeaways by 2-15%, the research indicated.
Dr Filippo Bianchi, from the innovation charity Nesta and the Behavioural Insights Team, together with colleagues from the University of Oxford in the United Kingdom, carried out research using a simulated delivery app and compared the results to a control app.
"Our findings suggest that simple interventions could help people select lower-calorie options on delivery apps without the need to remove less healthy options,” he said.
"This doesn’t mean that we always have to swap pizza for a green salad, even initiatives that make it easy to make small changes to what we eat could help to slowly reduce obesity, if delivered at scale.”
The randomised controlled trials included 23,783 adults who were users of food delivery apps.
In one trial looking at portion size, some 6,000 people were randomly assigned to either being in:
- A control group (meaning they just ordered what they liked)
- Being presented with a small portion size as the default
- Being presented with a small portion size as the default, plus using the word "regular", instead of "small", and
- Being presented with a small portion size as the default, plus using the word "regular" size and availability (i.e. the introduction of an additional "extra small" portion size option).
The study found that those in the control group ordered a meal that contained, on average, 1,411 calories.
All the other groups led to people significantly reducing the calories in what they ordered by an average of 5.5% (78 calories per order for the default option) to 12.5% (177 calories for the combined group).
A second trial then tested four interventions that repositioned foods and restaurants to make lower-calorie options more prominent on the app.
This study included 9,003 adults randomly allocated to either a control group (restaurants and foods listed randomly), or other groups with lower-calorie food options listed at the top of menus, lower calorie restaurants at the top of the restaurant selection page, or other combinations.
The study found that those in the control group ordered a meal that contained, on average, 1,382 calories.
Compared to this, all the other interventions significantly reduced the total calorie content of orders.
Putting both food and restaurants that display lower calorie options at the top of the app was the most effective, leading to an average 15% (209 calories) reduction per order.
The researchers said one important intervention that took into account the cost of food, cut calories by an average of 8% (117 calories), while also increasing the price of the basket, which is good for businesses.
The final trial tested the impact of using seven different designs of calorie labels to encourage the selection of lower-calorie options in 8,780 adults.
Compared to the control app (no calorie information provided), five out of seven labels significantly reduced the calorie content of orders ranging from an average of 2% (33 calories per order) to 8% (110 calories).
A further study on 20 adults then looked at how best to get people to accept the use of calorie labels in food delivery apps.
It suggested providing a filter that allows users to switch calorie labels on and off; communicating recommended energy intake per meal (e.g. 600 calories), and avoiding using things such as red fonts to "judge” people on their high-calorie meals.
Dr Bianchi said: "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 minimising effects on businesses and on cost-of-living concerns for consumers.”
UK National Obesity Forum chairman Tam Fry said: "This meticulous research ticks all the boxes.
"When the app allows the customer to avoid opting for unhealthy choices and directs them to lower calorie options, this is just what the doctor ordered.
"It is reasonable for the app to be able to hide calorie counts for people who find that they add to their eating disorders, or simply, annoy them.” – PA Media/dpa