Every American is responsible for about 5.6 tons of carbon dioxide releases a year, according to the Union of Concerned Scientists. An easy way to get started in correcting that is to use Bon Appetit's low-carbon-diet calculator. This national food service company's local and sustainable cafeteria choices are all the rage on college and corporate campuses, and its non-profit foundation has developed this practical and educational tool for individual menu planners.

How it works:  On the website, you are presented with a cast-iron frypan and photos of various meal options for breakfast, lunch, dinner and anytime. You click and drag your choice into the pan, and its carbon food points appear in the right hand column. In this way, you can tot up your daily carbon total the way you would calories. The company developed its point system using national averages for distances North American ingredients (except for tropical fruit) are transported, and trucking or shipping rather than air freight. They note that their points probably err on the light side, since much of our food is flown across country or from abroad. A  high carbon diet is 4500 points; eaten every day, this would release the equivalent of 3 tons of CO2 a year, Bon Appetit says. To make a positive difference, they advise keeping to 2500 points or lower a day.

Even if you don't like math, the calculations are easy and fun. For breakfast, an omelet with vegetables and cheese will cost you 1635 points, while a cereal with banana is 1148. For lunch, pepperoni pizza weighs in at 1208; a cheeseburger and fries, 2000. The Chinese chicken salad is lots lighter at 628. And consider local versus distance sourcing:  Fresh wild salmon from your region is a mere 75 points; shipped or trucked across country, it'll cost you 1,000. Grilled local vegetables in season (and this is the farmers' market season!) get a 95; if they come from a hothouse, it's 767.

See a pattern? You're right. Red meat and dairy products are carbon costliest, not least because ungulates (cows, goats, sheep) release tons of methane, a global warming gas that's 23 times more potent than CO2. And because of fewer fossil fuels burned in transport or greenhouse cultivation, local food in season is carbon lighter.

Try it yourself, and learn lots more, at Bon Appetit's Circle of Responsibility website. Bonus: Because the lowest carbon foods are fresh produce rather than fatty animal products or processed, sugary foods, we look forward to losing our last five bikini-busting pounds, as well.

This article originally appeared in Plenty in June 2008. The story was moved to MNN.com.

Copyright Environ Press 2008

Calculating your carbon food-print
Read about which foods you eat travel the farthest.