There is an interesting study from Cornell University:

Eating less, eating local and eating better could slash U.S. energy use, CU study finds

“We could reduce the fossil energy used in the U.S. food system by about 50 percent with relatively simple changes in how we produce, process, package, transport and consume our food,” said David Pimentel, professor emeritus of ecology and agriculture in the College of Agriculture and Life Sciences at Cornell.

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