1. Principles for Purchasing Outdoor Food Rations: Purchase food according to the principles of hygiene, sufficiency, nutrition, ease of consumption, ease of transport and storage, minimal waste production, and cost-effectiveness.
2. Scientific Allocation Principles for Outdoor Food: For breakfast, lunch, and dinner, allocate 20%, 50%, and 30% of your daily food supply respectively.
3. The energy and calories the human body consumes each day come 60%–65% from carbohydrates (rice, noodles, starches, potatoes), 20%–25% from proteins (vegetables, fish, meat), and 10%–15% from fats (meat).
4. A normally healthy person living in the city requires about 1,500–2,000 calories per day.
5. During spring, summer, and autumn wilderness hikes, approximately 2,500–3,000 calories are needed, requiring about 0.8–0.9 kg of food to meet the body’s caloric needs.
6. In winter wilderness hiking (low intensity), about 3,500–4,000 calories are needed, requiring about 0.9–1.0 kg of food to meet the body’s caloric needs.
7. Winter mountaineering (low intensity) requires about 4,500–6,000 calories, needing about 1.0–1.1 kg of food to meet the body’s caloric needs.
8. If you are active in winter or harsh weather conditions, carrying a 20 kg load and ascending over 500 meters in elevation, you will need at least 10% more calories than for low-intensity winter mountaineering, requiring more than 1.1 kg of food to meet the body’s caloric needs.
The above calorie consumption data may vary slightly depending on age and gender.
For example: Males aged 15–18 consume about 2,755 calories, those aged 19–45 about 2,555 calories; females aged 15–18 consume about 2,110 calories, those aged 19–45 about 1,940 calories.
Vitamin Sources and Functions in Various Foods:
1. Foods rich in Vitamin A: carrots, dairy products, fish oil. Function: Supports growth and development, enhances eye function (helps prevent snow blindness).
2. Foods rich in Vitamin D: dairy products, butter (with ample sun exposure). Function: Calcium supplementation, promotes metabolism.
3. Foods rich in Vitamin E: dairy products, plant oils, refined rice products. Function: Prevents arteriosclerosis, acts as an antioxidant.
4. Foods rich in Vitamin C: citrus and citrus-like fruits. Function: Boosts immunity, prevents arteriosclerosis, acts as an antioxidant.
5. Foods rich in Vitamin K: dark green vegetables, grains, meats. Function: Helps with blood clotting (prevents nosebleeds).
6. Foods rich in B1: dairy products, bananas. Function: Supplements carbohydrates and sugars, promotes metabolism.
7. Foods rich in B6: dark green vegetables, pears. Function: Increases protein, promotes metabolism.
8. Riboflavin: dairy products, grains. Function: Acts as an antioxidant.
9. Niacin: dairy products, grains. Function: Increases energy, promotes metabolism.
Preventing Dehydration While Marching
A person living in the city needs to replenish about 2,400 ml of water per day to maintain internal fluid balance. This includes about 1,400 ml excreted through urine, 600 ml via sweat glands, 300 ml through feces, and about 100 ml through other means such as saliva and nasal mucus.
1. When hiking, carry sufficient drinking water — about 3 liters per person per day. Adjust based on weather conditions, but always err on the side of bringing more rather than less. If you come across streams, ponds, ditches, or rivers for water replenishment, first observe whether the source is contaminated — check for presence of humans or animals, dead animals nearby, feces or caterpillar contamination, and whether the water is blackened or foul-smelling. Based on your observations, treat the water by methods such as sedimentation, filtration, or separation before drinking.
2. If you cannot confirm whether a water source is drinkable, it’s generally best to first apply a small amount of the water to your lips. Wait 3–5 minutes — if there is no numbness, itchiness, odor, or taste, then it is safe to drink.
3. When replenishing water in the wild, it is best to boil the water for five minutes if possible before drinking. Follow the principle of drinking small amounts frequently. Also, be proactive about drinking water — don’t wait until you’re thirsty. Drinking small sips (two or three at a time) is ideal. If very thirsty, you can shorten intervals between drinks and increase frequency, but avoid drinking large amounts at once. Excess water not absorbed by the body is wasted, burdens the heart unnecessarily, and is inefficient. For general hiking and outdoor activities, the optimal hydration strategy is about 250cc every 15 minutes.
4. During normal hiking periods, urination should occur about every four hours. You can monitor the color of your urine to assess your body’s dehydration status. Dark yellow urine with slight thirst and normal pulse indicates mild dehydration; dark amber urine, dry mouth membranes, thirst, and a faster yet weak pulse indicate moderate dehydration; severe dehydration shows as absence of urination, pale complexion, rapid breathing, thirst and drowsiness, and a fast, weak pulse.
Engaging in high-intensity, long-distance outdoor walking in hot climates leads to profuse sweating and body cooling. Although sweating is a natural regulatory response, insufficient fluid replacement amid heavy sweating leads to dehydration, impacting health. Mild cases result in thirst, reduced urination, fatigue, and muscle cramps, while severe cases can cause heatstroke, hyperthermia, or even be life-threatening.
Early symptoms of dehydration:
1. I feel "thirsty." (A sensation of thirst)
2. Urine output decreases, and urine color darkens,
3. Skin wrinkles, physical fatigue,
4. Decreased appetite, etc.
Symptoms of moderate dehydration:
1. Irritability, elevated body temperature,
2. Increased heart rate, dullness, difficulty concentrating,
3. Decline or distortion in motor or movement coordination, increasing the risk of sports injuries.
When dehydration reaches the above state, it indicates that it has already affected human cells and tissues, and the cells are dehydrated — this is what modern sports medicine often refers to as "body thirst." If not corrected promptly, it may further develop into severe dehydration, heatstroke, or shock and other heat-related illnesses.
In outdoor sports, the top priority is to proactively “prevent dehydration.”
First, pay attention to the early symptoms of dehydration. Secondly, for susceptible individuals and those engaging in outdoor activities in hot climates, fluid intake should be supplemented in advance. Depending on the amount of sweating, small amounts should be taken frequently and adjusted as needed.
The latest sports medicine research finds it necessary to provide athletes with electrolyte-containing sports drinks before, during, and after exercise, ensuring both health and improved physical performance. This fluid replacement principle also applies to all individuals who sweat heavily and young sports enthusiasts.
Research shows that when body fluid loss reaches 1%, athletic performance declines, the risk of heat-related illness increases, physical recovery slows, and susceptibility to infection rises. When fluid loss reaches 2%, athletic performance drops by 30%, and the likelihood of heat illness and sports injuries increases. To prevent the physiological impacts of dehydration, many schools schedule physical education classes after other lessons, which aligns more closely with human physiological principles.
How to determine the amount of lost body fluid? How to replenish the lost fluids? The general method is weighing: weigh yourself before and after exercise, and the difference in weight equals the amount of sweat lost during the activity. The amount of fluid to be replenished should be based on the weight lost that day — for every 1 kg of body weight lost, at least 1500 ml (1.5 liters) of fluid must be consumed to correct dehydration. Based on experience, basketball may result in 0.9–1.6 liters of sweat loss per hour, soccer 0.6–2.42 liters per hour, and cycling can also lose 0.62–1.25 liters per hour. To effectively correct dehydration, you need to replenish 1.5 times the amount of fluid lost.
The American College of Sports Medicine recommends drinking 500 ml of fluid two hours before exercise. In hot summer conditions, 750–1000 ml can be consumed two hours prior. Generally, you can drink 200–400 ml of an electrolyte-containing beverage before exercise or going out in the summer, then consume 150–250 ml of an electrolyte sports drink every 15–20 minutes during the activity until exercise or sweating stops. The remaining fluid intake can be completed within 6–12 hours.
What is the ideal fluid replacement alternative? From medical and physiological perspectives, to prevent and correct dehydration, fluids must contain two components: an appropriate amount of electrolytes and carbohydrates. Drinking plain water alone cannot effectively correct dehydration or restore energy.
First, plain water contains no electrolytes. When large amounts of plain water enter the body, they dilute plasma electrolyte concentrations and reduce stimulation of osmotic pressure receptors in the central nervous system and vascular walls. The feeling of thirst may disappear, but the cellular dehydration remains unaddressed — that is, "body thirst" is not corrected. Many people have experienced that after drinking plain water and sweating heavily, they still feel fatigued, drowsy, or have poor appetite. Drinking carbonated beverages after exercise is also unsuitable because these drinks not only lack electrolytes but the gas creates a bloated feeling in the stomach, hindering adequate fluid replenishment and absorption — again, "body thirst" remains uncorrected. Drinking high-sugar fruit juices during exercise is also inappropriate, as excessive sugar not only fails to relieve "thirst" or "body thirst," but may also cause stomach discomfort.
Sports drinks containing appropriate amounts of electrolytes such as sodium and potassium, along with carbohydrates, are the most suitable alternatives. The right levels of electrolytes and sugar concentration stimulate drinking, accelerate intestinal fluid absorption, provide energy for exercise, and promote recovery from dehydration. The most representative examples include Gatorade (or Pocari Sweat) sports drinks in the United States. Every year, funded by the Gatorade Sports Science Institute, top global sports medicine experts, sports physiologists, and nutritionists gather specifically to study the relationship between sugar and electrolyte concentrations in sports drinks and sports physiology, as well as the effectiveness of sports drinks in fluid replenishment. Some findings are officially published as positions of the American College of Sports Medicine. Scholars from China also participate in related research and conferences. According to current sports medicine studies, sports drinks containing 6–7% carbohydrates are considered most beneficial for human absorption and utilization.
Therefore, summarizing the above discussion, we emphasize: exercising in hot weather can easily lead to dehydration and heat-related illnesses. Whether you're an athlete or not, any activity that causes sweating requires attention to fluid replenishment to maintain health. Drink sufficient fluids before, during, and after exercise. Whenever possible, choose sports drinks with appropriate amounts of sugar and electrolytes.