Communicating Evidence about the Causes of Obesity and Support for Obesity Policies: Two Population-Based Survey Experiments

Public support for numerous obesity policies is low, which is one barrier to their implementation. One reason for this low support is the tendency to ascribe obesity to failings of willpower as opposed to the environment. Correlational evidence supports this position. However, the experimental evidence is mixed. In two experimental studies, participants were randomised to receive no message, messages about the environment’s influence on obesity (Study 1 & 2), or messages about the environment’s influence on human behaviour (Study 1). We investigated whether communicating these messages changed support for obesity policies and beliefs about the causes of obesity. Participants were recruited from nationally representative samples in Great Britain (Study 1 & 2) and the USA (Study 2) (total n = 4391). Study 2 was designed to replicate existing research. Neither study found evidence that communicating the messages increased support for obesity policies or strengthened beliefs about the environment’s role in obesity. Study 2, therefore, did not replicate two earlier experimental studies. Instead, the studies reported here suggest that people’s beliefs about the causes of obesity are resistant to change in response to evidence and are, therefore, not a promising avenue to increase support for obesity policies.

choose unhealthy food.
Put simply, our food environments play a large role in causing obesity.

Availability and cost + images
Everyone makes choices about their own behaviour, but the situation and environment influences what choices are available. People only engage in the activities and behaviour that are available. In some parts of Great Britain, the options are different to those available in other parts. If people need to get to work and the only options are driving or catching a bus, then they will choose one of these two options. Consumption of single-use plastic has increased dramatically in recent years with the rise of take-away drinks and food, and pre-packaged fruit and vegetables. Therefore, aspects of the environment play a role in the general behaviour that people engage in.

Behaviour (b):
Cost, Availability, and marketing + images You may think (have heard or read) that people have control over the choices that they make. For instance, you may believe that a person is in complete control of their choice of transport or how much they recycle. However, the evidence suggests that this is not the complete story.
Everyone makes choices about what they do day-to-day but our environments have a strong influence on this.
While personal choice does play a role, it only operates inside a much larger system of choices that are presented to us within our environments.
If engaging in a given behaviour is cheaper, more widely available, and heavily marketed, research shows that people are more likely to choose this option. For example, if buying coffee in single use plastic cups is cheap and more convenient to use than multiple use plastic cups then people are more likely to use them. If there are no cycle lanes and public transport is too expensive, then people are more likely to choose driving a car despite it being less environmentally friendly.
Put simply, our environment plays a large role in our day-to-day behaviours and choices.
Note. The images used in Group 3 and 4 were purchased from Shutterstock and the images used in Groups 5 and 6 were purchased from IStock. All are royalty-free and we therefore have rights to use them in our research and to share in this file.

Covariates
The first set of sensitivity analyses were those in which there were no covariates in the models. Across most analyses, the main pattern of the results remained the same. There was no evidence that the Obesity message (

Outliers
The second set of sensitivity analyses were those in which outliers were not excluded.

Study 2 interventions
Group 2: Obesity (a) [31]: "Everyone makes choices about what they eat, but the food environment influences what choices are available. Currently, highly processed foods that are high in sugar and fat are easily available and much cheaper than healthier foods such as fruits and vegetables. There are also parts of [America/England] in which there is limited access to grocery stores and fresh foods, and high availability of fast food restaurants and convenience stores that sell less healthy food. Restaurant portion sizes have increased in recent years, leading people to eat more food overall, and research has indicated that food advertisements and marketing increases consumption of unhealthy foods. Therefore, aspects of the food environment play a role in causing obesity." Group 3: Obesity (c) [32]: "Lately there has been a lot of talk about the factors that influence food choices in [America/England]. For example, food advertising can lead to the selection of unhealthy food and beverages. Certain food additives, such as extra salt, sugar, and caffeine, can also increase the desire for unhealthy food. And the placement of snack food and sugary beverages at checkout counters, especially in non-grocery retail stores, can often result in unintended food purchases and overeating. Consumers should be able to make their own dietary choices. But they also need to be free from the influence of heavy advertising, exposures to habit forming food ingredients, and invasive food product placement." Table S5. Descriptive statistics (mean [SD]) for the primary and secondary outcomes by country and randomised group

Covariates
We performed sensitivity analyses to test the robustness of the main results under different analytical decisions. The first set of sensitivity analyses were those in which there were no covariates in the models. Across all analyses there were no substantive differences between the main results and these sensitivity analyses. Namely, there was no effect of the There was no effect of the Obesity message (

Outliers
The second set of sensitivity analyses were those in which outliers were not excluded.

Supplemental materials
There were no outliers in the following variables: support for Discouraging policies, the belief that the environment influences obesity, the belief that genetics influence obesity, or the belief that a lack of willpower influences obesity. Sensitivity analyses were therefore not conducted for these variables.

Supplemental materials
. Note. These models control for gender, age, country, BMI, and group.