Why have sustained increases in obesity and type 2 diabetes not offset declines in cardiovascular mortality over recent decades in Western countries?

The majority of Western countries have reported large falls in cardiovascular diseases (CVD) mortality rates since the 1970s. Yet since the 1980s, they have also experienced two-fold or three-fold increases in the prevalence of obesity and type 2 diabetes--both considered substantial risk factors for CVD. So why have these increasing risks apparently not impacted on CVD mortality falls? This viewpoint outlines the main factors involved; examines recent trends and apparent contradictions; offers some explanations for the trends; discusses how more usefully complex epidemiological models might lead to clearer evidence; offers some explanations for the trends; and explores the implications for CVD prevention.