If every American skipped meat and cheese one day a week, environmentally it would be the same as the country driving 91 billion fewer miles a year. That's the figure calculated by the Environmental Working Group, which in a report out today urges the nation to eat less meat and cheese, both for health and the environment.

The call joins a growing movement advocating once-a-week meat-free meals, from an International Meatless Monday campaign and a European Veggie Days movement to decisions by some Catholic bishops to suggest a return to the no-meat Fridays of old.

The EWG report is the most recent in a long list calculating the greenhouse gases emitted in food production.