MRE has a rich history, which dates back in 1975. It was an idea that was born out of world war one. Back then, solders used to dry cooked food and carrying them using cloths and handkerchiefs. At the same time, cooking happened when soldiers were at their camps, which made it difficult to cook and eat in the battle field.
To make the long story short, in 1975 the Department of Defense adopted Combat ration, (Known as Department of Defense battle ration). Back then they were not called MRE. Large scale production began in 1978 and delivered in 1981, which was known as MRE I. A field study was conducted before 1978.
The MREs were consumed three times each day by the soldiers and they did not eat anything else. They rated the ration as acceptable, and the intake was low; about 60.5% of calories were ingested.
After the test and others that were conducted later, some changes were made in 1988, with the MRE XVIII. After few more field tests, even more improvements were made with the MRE X. MRE X saw the introduction of hot source and production of freeze-dried coffee, which replaced the old version mil-spec coffee spray-dried.
From that time, MRE began to gain popularity, and this is why there are also civilian MREs. Civilian MREs can be found in local stores and anyone can get them.