Competing interests: SC is the Chair of Health Equalities Group, Vice Chair of ASH Scotland, and sits on the Obesity Action Scotland steering group. LD is the Deputy Faculty Advisor as part of a fellowship of the Faculty of Public Health, sits on British Medical Association committees and holds an honorary contract with Cardiff University. SVK is joint editor-in-chief of the Journal of Epidemiology and Community Health; holds grants from the Medical Research Council, Scottish Government Chief Scientist Office and the European Research Council; and sits on the Obesity Action Scotland steering group. MvS declares funding from the Centre for Pesticide Suicide Prevention via a grant from Open Philanthropy, at the recommendation of GiveWell. CV has provided and received payment for consultancy services to Strategia Group and Our Future Health unrelated to the present work.