The shelf life for a "Meal Ready to Eat," as the MRE field ration is known, is approximately three years. Due to the fact that the items contained in an MRE are not freeze-dried or dehydrated, it is possible for spoilage to occur after the shelf life.
Improper storage of the ration in extremely hot or cold environments can significantly decrease the shelf-life. Exposure to 100 degrees Fahrenheit or more can reduce it to nine months.
These self-contained field rations were developed by the United States military after the Vietnam War. Prior to their adoption, standard field rations were heavy canned items that were not nutritionally balanced. The lightweight plastic pouches of the hydrated MRE kits weigh 18 to 24 ounces apiece, depending on the food items.