Higgins (2005) has shown that increased human physical activity in the USA could lead to both improvements in physical health and reductions in oil consumption by motor vehicles, thereby also reducing carbon emissions. It is an intriguing idea and, as the health costs of obesity are so high, the potential health and environmental savings could be vast. These questions deserve wider attention, as all the trends suggest that consumption of both fossil fuels and food calories (combined with more sedentary lifestyles) will continue to rise in the coming years.