http://www.army.mil/usapa/epubs/pdf/r40_25.pdf2–2. Nutritional standards for operational and restricted rations
Operational and restricted rations are designed for military personnel in a wide variety of operations, in widely varied
settings, for limited time periods. They provide the entire diet for military personnel during sustained operations. The
NSORs are based on the MDRIs and are designed to support the special nutritional requirements for various actual or
simulated combat situations. Personnel involved in operational ration development will use these standards in the
development, procurement, and evaluation of operational and restricted rations. Table 2-2 prescribes the NSOR.
a. Operational rations include the individual ration (Meal, Ready-to-Eat (MRE)) and group feeding rations (T-ration,
Unitized B ration, and Unitized Group Rations (UGR-A and UGR-H&S (heat and serve)), and are designed to be
nutritionally adequate. Operational ration menus will be designed so the menus, when averaged, meet the NSOR. The
calculated or assayed nutrient content of edible portions of food as offered for consumption will be compared to the
NSOR. Total calories from fat should not exceed 35 percent of calories for these rations.
b. The MRE may be consumed as the sole ration for up to 21 days. After 21 days, other appropriate rations (for
example, the UGR-A, UGR-H&S) will be included in the daily mix of rations. This policy is based on extensive
biochemical evaluations of soldiers consuming MREs for 30 days during field training. No degradation of performance
or nutritional deficit was found before 21 days. When the MRE is the sole ration, units will provide supplements and
enhancements (for example, bread, milk, and fresh fruit) whenever feasible.
c. Some operational rations are designed for special situations. These rations provide for the increased nutritional
requirements imposed by exposure to an extreme environment. This includes the Meal, Cold Weather.
d. The nutritional standards for operational rations do not apply to restricted rations. Restricted rations are nutritionally
incomplete rations used in certain operational scenarios, such as long-range patrol and reconnaissance, when troops
are required to subsist for short periods (up to 10 days) carrying minimal weight. Restricted rations include the Food
Packet, Long-Range Patrol ration. Nutritional standards for restricted rations are outlined in table 2-2.
e. The NSOR do not apply to survival rations. Survival rations include the Food Packet, Survival, General Purpose,
Improved (GP-I) ration; the Food Packet, Survival, Abandon Ship ration; and the Food Packet, Survival, Aircraft/Life
Raft ration. The GP-I contains 1447 calories. The Food Packet, Survival, Abandon Ship ration and the Food Packet,
Survival, Aircraft/Life Raft ration both contain approximately 300 calories, and are strictly short-term survival rations.
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I wonder how long they were eating the MREs only.