Increases in the prevalence of obesity have led to calls for policy interventions in the United Kingdom. Little is known, however, about how the public explains overweight, or their support for interventions. Our research team recruited 500 adults (≥18 years of age) across the United Kingdom to complete a cross-sectional survey asking about beliefs concerning the causes of excess weight, and support for particular policy interventions. Respondents completed questionnaires in their homes with the assistance of an interviewer. Results suggested that support for policy interventions was greatest when responsibility was attributed to factors beyond individual control, with support for child-focused interventions particularly high. The relationship is more complex than previous studies suggest, as believing in the over-availability of unhealthy foods predicted higher support for policy interventions, whereas beliefs in structural explanations, such as cost, had little influence on support. Recognition of this complexity may help to design more effective future policies to tackle obesity.