The following is an article from Princeton University on snow camping and survival. It covers the different calorie requirements you need when traveling or living under extreme conditions. You can find some additional information on cold weather survival at the following links, Hypothermia, How to Dress to Avoid It, Wind Chill and How it Can Affect You.
Planning food for winter activities you must take into account the great demands the cold weather and physical activity placed on the body along with the difficulty of preparing foods in the winter (it takes time, stove fuel) and having a menu which appeals to the group). Appetite is generally reduced during winter activity even through the food needs of the body have increased. If the meal isn’t appealing, it won’t get eaten. In some situations you literally need to force yourself to eat.
All foods are made up of varying proportions of the three basic food types – carbohydrates, fats, proteins, and water, vitamins and minerals. Each of the three major types can be converted into simple sugars and burned by the body to produce energy but the time required for conversion increases as the complexity of the molecule increases, so carbohydrates are quicker to convert than proteins and proteins quicker than fats.
|Dietary Percentage for Winter Camping||Food Type||Nickname||Description|
|50%||Simple Sugars||kindling||5 calories/gram (1,800 cal./lb.) – released quickly.|
|Complex Carbohydrates||sticks||5 calories/gram (1,800 cal/lb.) – released quickly. They are easy to digest. Candy, cereal, bread, rice, macaroni, dried fruit, vegetables.|
|20%||Protiens||logs||5 calories/gram (1,800 cal/lb.) – generally released slowly. Proteins are primarily used for maintenance and building of body tissue. Meat, fish, cheese, milk, eggs, nuts, grains.|
|30%||Fats||logs||9 calories/gram (4,100 cal/lb.) – released very slowly but are useful because they release heat over a long period. However, it takes more energy and more water to break down fats into glucose. Margarine, nuts, cheese, eggs, and fats from pepperoni, salami.|
Vitamins and Minerals – are generally found in most foods we eat and for a trip less than 7-10 days no special resources are needed. For longer trips and expeditions vitamin and mineral supplements are necessary. See a physician to get specific recommendations for expeditions.
General caloric requirements increase in the winter due to the energy expended in keeping the body warm. Caloric requirements for different activity levels are summarized below.
|Activity||Caloric Requirement (kg-cal/day)|
|Basal metabolism||1,500 calories|
|Sedentary occupation||2,500 – 3,000 calories|
|Three season backpacking||3,500 – 4,000 calories|
|Winter backpacking||4,500 – 5,000+ calories|
Keep in mind that there are definite individual variances on these figures based on age, body metabolism, health, etc.
Avoid taking fresh food in the winter (fresh fruit, vegetables, eggs). These all contain water and weigh a lot (and you have enough to carry). The exception to this is cheese, butter, or meats (needed for their high fat content). Take mostly dry foods (cereal, pasta, rice, wheat, oatmeal,) baked goods (brownies, cookies), or freeze dried foods (expensive but very lightweight and quick to cook which can save on stove fuel).
1. Breakfast – should not be a complicated meal but should be a complete one since it supplies the foundation for a full day’s work. Time is also a factor since you probably want to get up and moving. Just standing around in camp in the early morning (cold) hours only leads to cold feet and bodies. Since the easiest thing to cook is water it is best to go for items which can be made in each individual’s cup. Suggestions include: instant oatmeal with hot milk & margarine, hot Tang, Granola with hot milk, hot Jello, hot chocolate with extra milk & margarine.
It is best to supplement some of these items with extra powdered milk to add additional protein and margarine for fats. This is the meal to be careful not to dump too much sugar into the bloodstream at once, but rather to eat a good mix of all three major food types. The sugars will get you started and the proteins and fats will keep you going through the morning.
2. Lunch – There are two approaches to lunch on a winter trip. One is to stop for a traditional lunch and take a long break. This means cessation of activity which can lead to people getting cold. Additional layers would need to be put on and taken off. All of this adds up to a lot of time. But this also allows time for exploring an area and taking it easy. You can break out the stove and cook up a hot meal if you like. The other approach is carrying a personal lunch which can be eaten throughout the day, at scenic points, water stops, clothing breaks, etc. The second approach minimizes the amount of time people would be standing around, but also doesn’t provide a major rest stop. In both cases you should include all the food groups by having some of the following items: meats, cheeses, nuts, dried fruit, raisins, cookies, candy, granola bars.
In the case of an “eat through the day lunch” a general formula is to take the following per person per day:
- 1/2 – 3/4 lb. GORP – raisins, peanuts, M&M’s, sourballs coconut, chocolate morsels etc.
- 1/4 – 1/2 lb. Lunch Meat and/or Cheese – cut into bite size chunks so you don’t break your teeth
- Other items include cookies, brownies, peanut butter, bagels, etc.
3. Dinner – It is often good to start dinner with an instant soup or a hot drink that can be made in each persons’ cup. This gives some internal warmth while waiting for the main course. In the winter, the main dish is usually some form of one pot glop/stew. This is to save time and stove fuel. A glop starts with a soup or gravy base, and includes a starch (rice, noodles), some vegetables (frozen vegetables keep well on winter trips), whatever protein you are carrying (lunch meat, cheese, canned chicken, tuna). This should be spiced to make it tasty. Remember, at the end of the day you will be more tired than hungry and having an interesting meal is essential to get you to eat.
The other approach to dinner is freeze-dried foods. These have the advantage of simply adding the dish to boiling water so less fuel is needed and they weigh very little. There are a number of companies offering these items. They are generally more expensive than what you would pay for basic staples like rice & noodles. Be aware of portion size. Some companies give an unrealistically high estimate on how many their meal pack will feed.
The meal is concluded with hot drinks (tang, tea, hot chocolate, jello etc.) and possibly dessert. At the end of the meal water should be melted/heated up for personal water bottles at night. (See water section below).
Dehydrated foods (which are different than freeze dried are not recommended because they require large quantities of water to rehydrate them.
4. Food for sleeping – you need to take some of your lunch for the next day to bed with you. This allows fresh items like the meat and cheese to thaw. If you wake in the middle of the night and are cold (or just before you go off to sleep) it is best to eat proteins. The protein will be broken down more slowly so the heat will be released over a longer period of time. If you eat a sugar, you will get a quick “heat high” and then your body temperature will drop back down, sometimes falling below its previous level.
Comments – While i agree with the percentages and types of food, I personally would make a few changes in their suggestions. I would try to use more honey and less white sugar.
1) Do not eat snow! It takes an incredible amount of energy to transfer water from one state to another (solid to liquid). You are burning up too many calories to do this which can quickly lead to hypothermia.
2) Water may be obtained by digging a hole in frozen lakes or streams where there is running water beneath the ice. Be careful about falling in. Remember, in most cases water will need to be purified from giardia and other bacteriological contaminants (see below).
3) Snow can be melted on a fire or stove to make water. It should be clean snow, no yellow (urine) or pink (bacterial growth). Because it takes so much energy to convert from one state to another you should have some water in the bottom of your container. Heat this water up and add snow to it slowly so it turns to slush and then water. This is much more efficient. If you dump in straight snow, you will only burn the bottom of your container and not make any water. By volume it takes about 10 quarts of snow to make 1 quart of water. Snow does not need purification.
4) Winter Solar Water Collector – In a spot that will remain sunny for several hours, dig out a depression in the snow about 2 feet across and 1 foot deep. If possible, line this depression with a foam pad or other insulation (not essential but it speeds the process). Then spread a dark plastic bag (trashbag) over the depression forming a shallow dish pan. All over the raised margins pack clean snow. Drawn by the dark plastic the sun’s energy will melt the snow and water will collect in the depression.
5) Water in a pot can be stored overnight by placing the pot lid on and burying the pot under a foot of snow. Snow is such a good insulator that it will keep the water from completely freezing even in sub-zero temperatures.
6) Personal Water – You should have a water bottle with a wide mouth, otherwise the opening will easily freeze up. During the day you should carry at least one bottle next to your body (usually with a shoulder strap arrangement). Your body heat will keep it from freezing and the bottle is handy to rehydrate yourself throughout the day. Insulated water bottle holders are available for this. Other bottles can be kept upside down in an insulated container (sock etc.) preferably in an outside pocket on your pack. Being upside down will keep the mouth of the bottle from freezing. Keep in mind that the lid must be on tightly or water will leak all over the place. A cold water bottle may have ice crystals in the threads. As the bottle heats up from body temperature the ice may melt causing the cap to loosen also the lid may expand with heat causing leakage. At night keep your water bottles in your sleeping bag to prevent them from freezing.
7) Getting Water – sometimes filling pots and water bottles from a stream or lake is a major expedition in itself. Make sure that the area you plan to get water from is secure. Avoid steep banks that might lead to a plunge and make sure any ice is sufficiently stable to hold your weight. Also make sure you don’t get your mittens soaked with icy water. A loop of string tied tightly around the water bottle neck will allow you to lower a bottle in by hand or with a ski pole or ice axe. Don’t trust pot grips on a large pot, with mittens you can lose your grip and your pot. Fill the pot up part way and then use a water bottle to top it off. Mark the area so you can find it next time.
Note -Tomorrow I will post an article on water purification under cold weather conditions.