Measuring and evaluating the environmental costs of the different methods of food production is not easy. However, the most accurate and fundamental way is to examine the total energy use involved in production. We will be looking at the energy input versus energy output, the measurements in Kcal.

Animal production shows that for every 1 Kcal of energy input, chicken generates 18.1 Kcal of energy, milk generates 20.6 Kcal, eggs 11.2, beef 6.4, pork 3.7, lamb 1.2, farmed salmon 5.7, and tuna 5.8 Kcal. Plant production shows that corn produces 250 Kcal, potatoes 123 Kcal, and apples produce 110 Kcal per every 1 Kcal. Surprisingly, soy is able to generate 415 Kcal of energy output to every 1 Kcal, which is the highest not only among its agricultural counterparts, but also compared to most meat foods. Also, soybeans normally take up about 6 to 17 times less land than meat to produce, while even intensive dairy operations require at least 5 times the amount of land to produce.