Nutrition in the Field

LAST UPDATED: October 18, 2017

Deployments and field operations demand a properly fueled and nutritionally maintained body—this could mean the difference between top performance and mission failure. Poor nutrition in extreme conditions (hot, cold, or high altitude) can lead to fatigue, rapid weight loss, injury, illness, and dehydration. Focus on eating foods that provide top mental and physical performance without compromising long-term health. View your mind and body as a weapon system. To be the most lethal weapon in the arsenal you need to be “nutritionally” fit.

Readiness begins in garrison/FOB

Maintain a performance diet and a healthy weight by practicing healthful eating. The foods you choose to eat affect energy, concentration, and memory. Optimize your nutrition before, during, and after deployment/field operations.

Primary ways to be nutritionally prepared for all missions:

  • Maximize energy stores! Low energy stores = fatigue!
  • Eat a high carbohydrate diet.
  • Avoid skipping meals—refuel every 4–5 hours at a minimum.
  • Stay well hydrated.
  • Minimize intake of heavily processed, high fat foods.

Performance nutrition tactics during missions

When on continuous operations it is important to fuel (eat). Warfighting requires you to expect the unexpected. An “empty tank” after a strenuous mission will be detrimental to the next mission.

Nutrition tactics during missions include:

  • Make time to fuel. Energy stores need to be restored with food regularly. Refuel often—every 3–5 waking hours.
  • Eat the most calorie-dense items in your ration first. If you don’t have a lot of time to eat or won’t get a break for a while, make it a point to eat a small amount when you have the chance.
  • Snack when you can—include carbohydrate and energy-rich choices such as dried fruits, nuts, and trail mixes when choosing pogey bait or save unopened snack items from rations to eat on the run.
  • Eat calorie-dense and nutrient–rich foods. This is especially critical when you’re exposed to cold and high altitudes. Your energy needs will be higher, and your appetite may decrease.
  • Drink fluids frequently, even when you are not thirsty. Monitor the color of your urine and watch for signs of dehydration. In extreme environments such as hot, cold, and high altitudes, increase your fluid intake.

Plan for the operational use of caffeine

  • In moderate doses, caffeine improves mental performance, mood, and marksmanship in the most stressful environments and has operational utility.
  • Caffeine is not useful to those already consuming over 300 mg per day. If you want to use caffeine for extended operations and you normally have a high caffeine intake, it will not help you when you need it.
  • The recommended “optimal dose” for caffeine is 200 mg—more is not effective. Doses over 200–300mg may produce initial symptoms of restlessness, anxiety, increased heart rate, and insomnia.
  • Higher doses can lead to more severe adverse reactions to include increased blood pressure, heart palpitations, dizziness, irritability, nausea, nervousness, jitters, and in some cases, death from caffeine overdose.

The table below provides guidance about proper caffeine dosing. If you decide to use caffeine dosing, remember to limit dose to approximately 200mg and stop dosing at least 6 hours prior to sleep.

Caffeine dosing recommendations
Circumstances Dosing
Sustained Ops (no sleep): 200 mg @ ~ 0000
200 mg again @ 0400 and 0800 h, if needed
Use during daytime (1200, 1600) only if needed
Night Ops with daytime sleep 200 mg @ start of night shift
200 mg again 4 hours later
Last dose: at least 6 hrs away from sleep period
Temporarily Restricted Sleep (6 or fewer hrs. of sleep) 200 mg upon awakening
200 mg again 4 hours later
Last dose: at least 6 hrs away from sleep period

Operational rations

Operational rations are designed for military personnel in a wide variety of operations, in widely varied settings, for limited periods. A variety of rations exist to meet unique mission requirements and include the most familiar ration, MRE™. MRE™ are made with real food and give you the most nutrition in the smallest package (approximately 1200–1300 calories per package). Some parts of the MRE™ may have extra nutrients and Soldiers should be encouraged to eat at least a part of each component of the MRE™ to get a well-balanced diet. The Combat Rations Database (Com-RAD) website provides nutrition information for MREs™ and other operational rations. This information can help you determine how much of or how many individual rations you need to meet nutrition needs in the field environment.

First Strike Ration

The First Strike Ration (FSR™) is a compact, eat-on-the-move assault ration designed for high-intensity combat operations. It is substantially lighter and more compact than the MRE™, and enhances Warfighter consumption, nutritional intake, and mobility. Developed to support operations lasting less than 72 hours, the FSR™ does not meet all of a Soldier’s nutrient requirements. Do not use this ration for more than 72 hours. The FSR™ is issued one per day, instead of the MRE™ distribution of three per day. Ask your Installation Registered Dietitian about the right ration for your mission profile.

Meeting nutritional needs in the field environment

Often during deployments and field training, calorie needs are higher due to increased physical demands and completing missions in extreme environments. Soldiers need to be aware of their need for more calories and ensure they are properly fueling their bodies. Use the charts below to estimate daily nutrition needs and additional calorie requirements for field-related activities.

Daily energy needs calculator

Enter the following information into the calculator to compute your daily calorie needs.

Step 1: Select your gender.

Step 2: Enter your weight in pounds.

Step 3: Choose your Activity Factor (AF) from the drop-down list.

  • Sedentary
  • Light to moderate activity
  • Heavy activity
  • Exceptional activity

Step 4: Choose your Environment Factor (ENF) from the drop-down list.

  • Normal
  • Heat
  • Cold
  • Altitude
  • Water Immersion

Step 5: Your results will be displayed on the Daily Calorie Needs line.


My Daily Energy Needs Calculator

Weight (in lbs):
Activity Factor (AF):
Environment Factor (ENF):
Daily Calorie Needs:
Example (male): 145lbs x 12 = 1740 x 1.5 x 1.1 = 2871 calories per day


Estimated calories burned per hour according to activity and body weight
Activity 100 lbs. 130 lbs. 175 lbs. 200 lbs. 230 lbs. 250 lbs. 280 lbs.
Walk, 3.5 mph (generally flat course) 430 cal. 559 cal. 753 cal. 860 cal. 989 cal. 1075 cal. 1204 cal.
with 0-25 lb. load 480 cal. 624 cal. 840 cal. 960 cal. 1104 cal. 1200 cal. 1344 cal.
—with 25-49 lb. load 570 cal. 741 cal. 998 cal. 1140 cal. 1311 cal. 1425 cal. 1596 cal.
—with ≥50 lb. load 630 cal. 819 cal. 1103 cal. 1260 cal. 1449 cal. 1575 cal. 1764 cal.
Walk, 4.0 mph (generally flat course) 500 cal. 650 cal. 875 cal. 1000 cal. 1150 cal. 1250 cal. 1400 cal.
—with 0-25 lb. load 600 cal. 780 cal. 1050 cal. 1200 cal. 1380 cal. 1500 cal. 1680 cal.
—with 25-49 lb. load 700 cal. 910 cal. 1225 cal. 1400 cal. 1610 cal. 1750 cal. 1960 cal.
—with ≥50 lb. load 780 cal. 1014 cal. 1365 cal. 1560 cal. 1794 cal. 1950 cal. 2184 cal.
Walk/jog, 5.0 mph (generally flat course) 830 cal. 1079 cal. 1453 cal. 1660 cal. 1909 cal. 2075 cal. 2324 cal.
—with 0-25 lb. load 900 cal. 1170 cal. 1575 cal. 1800 cal. 2070 cal. 2250 cal. 2520 cal.
—with 25-49 lb. load 1000 cal. 1300 cal. 1750 cal. 2000 cal. 2300 cal. 2500 cal. 2800 cal.
—with ≥50 lb. load 1070 cal. 1391 cal. 1873 cal. 2140 cal. 2461 cal. 2675 cal. 2996 cal.
Moving/lifting heavy objects 750 cal. 975 cal. 1313 cal. 1500 cal. 1725 cal. 1875 cal. 2100 cal.
General physical work 450 cal. 585 cal. 788 cal. 900 cal. 1035 cal. 1125 cal. 1260 cal.
Calisthenics (push up, pull up, etc.) 380 cal. 494 cal. 665 cal. 760 cal. 874 cal. 950 cal. 1064 cal.
Walk, 3.5 mph (uphill) 670 cal. 871 cal. 1173 cal. 1340 cal. 1541 cal. 1675 cal. 1876 cal.
—with 0-25 lb. load 690 cal. 897 cal. 1208 cal. 1380 cal. 1587 cal. 1725 cal. 1932 cal.
—with 25-49 lb. load 830 cal. 1079 cal. 1453 cal. 1660 cal. 1909 cal. 2075 cal. 2324 cal.
—with ≥50 lb. load 900 cal. 1170 cal. 1575 cal. 1800 cal. 2070 cal. 2250 cal. 2520 cal.
Walk, 4.0 mph (uphill) 770 cal. 1001 cal. 1348 cal. 1540 cal. 1771 cal. 1925 cal. 2156 cal.
—with 0-25 lb. load 810 cal. 1053 cal. 1418 cal. 1620 cal. 1863 cal. 2025 cal. 2268 cal.
—with 25-49 lb. load 890 cal. 1157 cal. 1558 cal. 1780 cal. 2047 cal. 2225 cal. 2492 cal.
—with ≥50 lb. load 1000 cal. 1300 cal. 1750 cal. 2000 cal. 2300 cal. 2500 cal. 2800 cal.
Brisk walk/jog, 5.0 mph (uphill) 980 cal. 1274 cal. 1715 cal. 1960 cal. 2254 cal. 2450 cal. 2744 cal.
—with 0-25 lb. load 1030 cal. 1339 cal. 1803 cal. 2060 cal. 2369 cal. 2575 cal. 2884 cal. 
—with 25-49 lb. load 1130 cal. 1469 cal. 1978 cal. 2260 cal. 2599 cal. 2825 cal. 3164 cal.
—with ≥50 lb. load 1190 cal. 1547 cal. 2083 cal. 2380 cal. 2737 cal. 2975 cal. 3332 cal.
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