If you'd like to cut down on your carbon footprint, have a peanut butter and jelly sandwich for lunch instead of a burger. That's the idea behind a new campaign cited by Green Options.

According to the campaign, you can eliminate 2.5 pounds of carbon production by opting for a PB&J instead of beef, chicken, or even tuna for lunch. Since I love peanut butter, this won't be much of a sacrifice as I've always made it part of my diet.

This got me to thinking that people pondering sustainability and energy efficiency usually consider the impact of the car they drive or kind, heating system they use, or even clothes they wear, but the energy impact of our diet rarely comes up.

Ethanol is criticized for being energy inefficient, as critics are quick to say that we don't have the agricultural resources to grow our fuel supply as lots of petrochemicals are used to grow corn and grain. But hypothetically speaking, we would have a lot more land to grow crops for fuel if the American diet weren't so meat-heavy. If we want to grow our fuel instead of importing it, then one of the quickest ways to do so would be through cutting back on the meat. The same arguments against corn for ethanol go double for corn meal used to feed cattle or chickens -- the energy value is not good.

Not only does it take more resources (water, and corn/grain that is produced with the help of lots fertilizer) to produce the same caloric value of meat as beans, tofu or other protein rich agriculture, but the cows are also producing greenhouse gases that contribute to global warming.

The meat that we eat "generates an estimated 18 percent of total human-induced greenhouse-gas emissions globally," according to a U.N. report released in December.

So as you can see, we are literally getting it at both ends by eating so much meat. While we are free to choose what we eat, it is fair game to consider how meat contributes to both fuel consumption and pollution as part of our study of sustainability.