food self-sufficiency The food self-sufficiency rate is a number that shows how much of the food consumed in Japan is produced domestically. There are two main ways to express it. The first is the self-sufficiency rate by item, which is calculated by weight. The second one is called the overall food self-sufficiency rate, which is calculated in units together. There are two main types. There are two types of total food self-sufficiency rates: calorie-based, which is calculated in terms of caloric value, and production-based, which is calculated in terms of monetary value. The other two are feed self-sufficiency rates. food self-sufficiency self-sufficiency rate by item ←←←←←←←←←←→→→→→→→→ total food self-sufficiency rates →→→→→→→↓ ↑ ➘Feed self-sufficiency ↓ calorie-based Calculated by weight. Calculated in monetary terms　→ production-based ↑Calculations in terms of calorific value How to calculate self-sufficiency rate by item 　＝Amount produced domestically(Gross domestic product)÷ Amount consumed domestically (domestic consumption-destination) domestic consumption-destination 　＝Gross domestic product＋Volume of imports －volume of exports－increase in inventories calorie-based food self-sufficiency rate 　＝Average daily domestic heat supply per person÷ Average heat supply per person per day As Japan's food self-sufficiency rate decreases...  Japan's low food self-sufficiency rate means that we are dependent on other countries for the low portion. It is estimated that 12 million hectares of land is needed to produce the agricultural products we are importing, which is about 2.5 times the amount of land that is currently used for agriculture in Japan. Furthermore, importing it means that it is being transported by ship or other means for that amount of space. That means that it emits carbon dioxide for it. Importing it means that we are also contributing to global warming.  Also, if something goes wrong in the country, or if you know that the relationship between the two countries has gone bad...you can't import the food, and Japanese food will be in demand, so prices will be higher and you won't be able to find it in the stores.