Communicating Evidence About the Causes of Obesity and Support for Obesity Policies in British and US populations: Two Population-Based Survey Experiments

Background: 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: beliefs about the causes of obesity are associated with support for policies that aim to reduce obesity. However, the experimental evidence for the causal nature of this association is mixed.

Methods: 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 policies to tackle obesity 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 two previously published studies.

Results: While the belief that obesity is caused by the environment was associated with support for obesity policies, neither study found evidence that communicating the messages increased support for obesity policies or strengthened beliefs about the environment’s role in obesity.

Conclusions: The current study replicates earlier studies reporting an association between beliefs about obesity and the environment but does not replicate two earlier experimental studies that suggested the association is causal. The evidence reported here suggests that people’s beliefs about the causes of obesity are resistant to change and therefore not a promising avenue to increase support for obesity policies.