According to a study by engineers Christopher Weber and H. Scott Matthews of Carnegie Mellon University, of all the greenhouse gases emitted by the food industry, only 4% comes from transporting the food from producers to retailers. The study also concluded that adopting a vegetarian diet, even if the vegetarian food is transported over very long distances, does far more to reduce greenhouse gas emissions, than does eating a locally grown diet. They also concluded that "Shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food." In other words, the amount of red meat consumption is much more important than food miles.