Here are the possible sources of food during an emergency. You should decide for yourself what is most reliable and cost effective. A normal person needs about 2,000 calories per day, and someone who is exerting themselves (eg, survival, search, and rescue operations) may need 3,000 - 4,000 calories per day.
1. The regular canned food in your pantry. Regular canned food, such as Hormel Chili, is cheap, tasty, easy to get, and will last a very long time. It's manufactured from reliable sources. You can buy what you would normally eat, and nothing will go to waste if you rotate your stock. Additionally, most canned food is packed in WATER, so you get a safe supply of fresh water with each meal. Almost all canned food is cooked as part of the canning process, so you normally can eat it straight from the can (without heating). Canned food also has a shelf life far beyond MREs or Emergency Rations (for example, according to Hormel, "the shelf life of [canned Hormel Chili] is indefinite as long as the seal remains intact", although the flavor may decrease). COST PER 2,000 CALORIES: about $2 - 6.
2. MREs. MREs are hard to get (due to ongoing military and recent civilian needs) and relatively expensive (between $6 - 8 per meal). Each MRE contains about 1200 calories and is relatively tasty. They also contain vital ingredients you need during heavy exercise (search and rescue ops), such as salt. Despite some claims by competitors, you DO NOT require water to eat an MRE. Only a small, non-essential portion of the meal requires water (the drink mixes). MREs will last 5 years only if stored at less than 50 degrees Fahrenheit. At 60 degrees, the shelf life is 4 years, and at 80 degrees, the shelf life is 3 years. At 100 degrees, the shelf life is only 6 months. COST PER 2,000 CALORIES: about $10 - 14.
3. Energy bars. Energy bars, such as Clif Bars or PowerBars are carbohydrate laden and sugar laden supplements that are intended to give you a boost after exercise and not intended to be real food. They are inexpensive (about $1.50 for 240 calories) but have a very short shelf life. Also, they normally lack fiber. You'll want some dietary fiber in a sustained emergency. COST PER 2,000 CALORIES: N/A - these are not meal replacements.
4. Emergency ration bars. Ration bars, such as Datrex or Mainstay, are relatively light weight and are able to accept temperature changes. However, they are moderately expensive. It is difficult to assess the nutritional facts about Datrex bars, because I have not seen the complete Nutrition Facts even though I've search for them. They appear to be flour, water, sugar, and fat, although there is no indication of how much of the carbohydrates are simple sugars vs. fiber (see above about Energy Bars, such as PowerBars). Additionally, although a 2400 calorie bar may keep you alive for 3 days, that's only 800 calories per day. If you have to rely on these bars for an extended time, 800 calories per day is not sufficient to sustain heavy activity, such as survival, search and rescue activities. Since you are not likely to eat these for the taste, after 5 years you'll throw these away and need to buy replacements - a real waste. Nevertheless, these bars definitely have their place in a go bag, in order to sustain you until you get to your main food supply (eg, your pantry). COST PER 2,000 CALORIES: about $7.
5. Dried fruits and nuts. Dried fruit is very expensive, full of sugar, and may be treated with preservatives. I know a lot of people who have had reactions to eating dried fruit (eg, skin flush, nausea), and that's something you don't want in an emergency. Nuts are great sources of calories and delicious, but a lot of people have life-threatening allergies to nuts - and even people who have never had allergies can develop them suddenly. Nuts are not a good source of carbohydrates. Additionally, even canned or sealed nuts have very short shelf lives (between 6 - 18 months, max, according to Planters' website). COST PER 2,000 CALORIES: about $14 - 20 for fruit, and about $8 for nuts.
6. Freeze-Dried (not "dehydrated") Camping Food. [2/17/2012, thanks to "Walker" for suggesting this category!] Freeze-drying is a process of cooling the food to temperatures about 50 degrees below zero to remove the water (note that "dehydrating" heats the food and is different). My comments relate to Mountain House brand, but other brands are probably similar. The nutrition of freeze-dried foods seems to be very good, with a balance of protein, carbs, and fat, although the fiber content is still a little low. They also are a little high in sodium, but you will need sodium (salt) in an emergency. I read a lot of good reviews of the taste, so I tested some and can confirm the taste is AMAZING, especially for a camping/emergency food. The shelf life of #10 cans of freeze-dried food is about 25 years (wow), and for the pouches is between 5 - 7 years. So what is the drawback? First, these foods require water to prepare. A pouch of 400 calories will take 2 cups of water, and a complete day's ration of 2,000 calories will take 8 cups. I tested using cold water (since cooking heat will not be available), and it works fine if you double the preparation time. I'm pretty sure drinking water will be in very short supply in my area after an earthquake. Also, these are relatively expensive (the most expensive alternative for food), but as "Walker" suggests, the long shelf life may make up for the expense. COST PER 2,000 CALORIES: about $26.
Only you can decide what you will need and what is best for you. I have a lot of pantry food, with some MREs and emergency ration bars for the go packs and car.
