Depends on what you had. The Bon Appetit Management Company has a super cool tool online calculator specifically geared to food (there are lots of online calculators to calculate your home, your car, or your air travel, but to my frustration they usually omit food)...but here's all you need to check out how cool your cuisine is-or isn't, when it comes to the planet. Log onto www.eatlowcarbon.org, drag and drop your meal onto the pan, and watch the thermometer rise depending on your choice. Cheeseburger? That's 4 lbs of carbon (measured in carbon equivalents), or about 1/5 of a gallon of gas. Switch to a grilled chicken sandwich and cut it by more than half-down to 1.5 pounds. If you choose a grilled veggie and hummus sandwich instead and thin your footprint even further (down to 0.6 pounds). Oh, and by moving your lunch down the "carbon thermostat", you just also made a healthier choice that can help you move your belt in a notch, too.