text: Nutritional Readiness
  8-56. The Natural Medicines database, a resource accessed through the Operation Supplement Safety
  website, is free for Soldiers. It provides in-depth information about dietary supplement products and
  ingredients based on the best available scientific evidence.
  ENVIRONMENT
  8-57. Nutritional requirements largely depend on environmental conditions. Hot or dry environments require
  different levels and types of nutrition than cool or moist environments. High altitudes demand different
  nutritional requirements than low altitudes, and so on. This section describes how nutritional requirements
  vary between environments as well as the conditions in those environments that drive specific nutritional
  needs.
  NUTRITION FOR MISSIONS IN THE HEAT
  8-58. Repetitive movement along difficult terrain with heavy gear, such as during land warfare operations,
  is challenging under any environmental condition, but is particularly grueling with extreme heat and
  humidity. Land warfare scenarios where Soldiers carry heavy loads or injured comrades increase overall
  effort and energy expenditure, as well as fluid and electrolyte needs. The major concerns during operations
  in a warm or hot environment are fluid and electrolyte balance.
  8-59. Working or exercising in the heat intensifies water and electrolyte loss through sweating. The amount
  of sweat and fluid lost depends on—
  * Environmental temperature and humidity.
  * Work rate.
  * Fitness level and acclimatization.
  * Volume and rate of fluid replacement.
  8-60. When the same task carried out in thermo-neutral environment (such as a range of temperatures of the
  immediate environment in which a standard healthy adult can maintain normal body temperature) is
  performed in a hot environment, energy requirements increase slightly due to the increased work to maintain
  thermal balance. When living or working in temperatures ranging from 86–104° F (30–40°C), energy intakes
  typically increase by 2.5–10 percent unless activity level decreased accordingly. However, heat-acclimated
  individuals likely will not have an increase in energy requirements.
  8-61. High work rates in hot, humid surroundings can significantly increase fluid and electrolyte losses.
  Losses of one to two quarts per hour or even more are likely when special clothing, such as chemical
  protective gear, body armor, or both are worn. The highest sweat rates reported exceed over five quarts (160
  ounces) per hour.
  8-62. Soldiers need fluids and need to drink early and drink often. Starting any operation without being
  adequately hydrated may increase the risk of performance mishaps. Some believe that relying on thirst is
  adequate for sustaining hydration, whereas others believe that thirst itself is an indicator of dehydration. For
  certain, failure to replace lost fluids from sweating results in dehydration and possibly heat injury.
  8-63. Leaders avoid forcing Soldiers to drink throughout training in a warm environment to ensure adequate
  fluid replacement. Too much water can result in hyponatremia. Effective leaders have a pre-determined
  drinking schedule to ensure Soldiers consume enough fluids. Soldiers ideally drink ¼–½ quart or liter (8–16
  ounces or 1–2 cups) of fluid every 30 minutes, and no more than 1 quart or liter (32 ounces or 4 cups) per
  hour.
  8-64. Obtaining body weights before and after activity can help determine fluid replacement needs. One
  kilogram weight loss requires 1,000 milliliters of fluid to restore fluid balance (or 16 ounces per pound weight
  loss). A fluid loss of 2-percent body weight can impair physical performance and mood, decrease appetite,
  and increase the risk of heat injuries. A 5-percent loss of body weight can decrease work performance by 30
  percent.
  8-65. Soldiers monitor their hydration in the field. In the field when it is difficult, if not impossible, to obtain
  a body weight, Soldiers use their urine color and smell to gauge hydration status. Dark yellow or smelly urine
  suggests some degree of dehydration. Soldiers then increase fluid consumption until urine becomes pale