Whether you are packing for a hike, camping trip, an emergency or simply stuck on a desert island, there are basic foods that we all need to be aware of for survival. Depending upon body size, genes and other unique factors, the average person may be able to survive without any food for 30-40 days if they are properly hydrated. Unfortunately we can only last about a week without water.

Our "must have" foods need to be high in energy, easy to transport, require no refrigeration or cooking and provide the necessary nutrients for survival. Here are some foods to add to your survival gear.

• Fats - Fats are highly concentrated sources of energy. Gram for gram, fat provides twice as much energy as carbohydrates and protein. Add these portable sources of fat to your survival list: nuts, canned fish, dried/dehydrated meat.

• Carbohydrates - Carbohydrates are essential in survival mode where you often burn more calories and reach exhaustion faster than normal. Carbohydrates are important for providing physical performance. Add these carbohydrates to your survival list: instant oatmeal, dried fruit (also high in vitamins and minerals) and granola bars.

• Protein - Complete proteins, which contain all of the essential amino acids are important to repair muscle tissue. In survival mode, especially if you are injured, you will need protein for healing. Quick and easy sources include tuna or salmon in a pouch, dehydrated/dried meats, like jerky and nuts. Protein bars are an ultimate survival food because they contain a lot of nutrition in a small package. No preparation is required for any of these as they can be consumed right out of the package.

Beans, a great source of protein, have high amounts of important nutrients for the body, including calcium and iron. Both dried and canned beans have a very long shelf life. Many varieties of canned beans require no preparation and are ready to eat right out of the can.

• Water and Electrolytes - Last but definitely not least is the need for water. You need about a gallon per day. This is especially important in extreme temperatures when you may perspire a lot. Perspiration can cause deficiencies of electrolytes which can lead to drowsiness, weakness, nausea, confusion and disorientation - not something you want when you are struggling to survive. Electrolyte tablets are great choices to include in your backpack because they are lightweight and easy to transport. According to the United States Search and Rescue experts, rationing your water wisely gives you the best chance of survival. It is advised not to drink on the first day and to work off the reserves of water in your system first. Over the next few days you should lower your daily water intake from 14 ounces to between 2 and 8 ounces.

• Prior Planning - Don't just plan to survive when lost; plan not to get lost or hurt. Packing the right food is just as important as selecting the right shoes and clothes. A day-pack stocked correctly can last much longer than a day. A map and compass are easy to get, inexpensive and light-weight, as are granola bars and water. The math is easy; 2-16-ounce bottles of water only weigh 2 pounds and according to the experts, that can last from four to 16 days. Some of my favorites, the "salt and sweet" type granola bars seem to be the best for having many of the ingredients mentioned above that you need for survival; fast to slow burning energy sources and salt for water retention (electrolytes). Hopefully you will never have to use your food survival skills! But just in case...

Dr. SeAnne Safaii, Ph.D., RD, LD, is an assistant professor at the University of Idaho.