This resource, although of historical value, may be a useful reference for those who might consider making their own man packable ration packs.
Food technology has advanced well ahead of what was available back in the day, but human nutritional needs are pretty much the same.
This resource is well illustrated, and an easy interesting read.
Although primarily concerned with Australian WW2 rationing systems, it does refer to the combat rationing systems of other countries in that era, including the American K Ration, and interesting commentary on German and Russian combat ration systems.
Well referenced for those wishing to explore further.
http://www.army.gov.au/~/media/File...1939-1945/Documents/Operational Ration O2.pdf
The Early History of Combat Ration Development (WW2 era)
Combat ration development during WW2 (mainly Australian, but including other nations also)