Rates of obesity and diet-related preventable diseases, including cancers and type 2 diabetes, are rising and require urgent attention. Although improving the healthiness of people's diets is paramount, only a minority of consumers read objective nutrition facts panels, and research suggests shoppers are being misled by nutrition-related information elsewhere on food labels. Conflicting empirical results and unclear evidence of how labels influence behaviour have confounded regulatory progress, leaving a serious public health debate unresolved. The proposed mixed-methods studies will provide the first insights into how consumers routinely use packaging information. Mobile eye-tracking technology will capture consumers' use of food labels in purchase decisions, which will be probed using in-depth interviews. These results will enable development and testing of alternative front-of-pack nutrition labels using innovative experimental research methods that overcome prior studies' limitations, and will provide the basis for food labelling that is currently failing to promote healthy choices.