How did you know I was a Jr?

Protein is the least efficient energy source, and has less energy per unit of weight(protein and carbs both have 4 calories per gram, but protein uses more energy to digest). Protein also requires the most water to metabolize, so is very undesirable, except possibly for long term survival situations. Fat is the most concentrated nutrient in terms of calories(9 cal/gram), so it is important for survival foods, but I'm pretty sure fats take more energy to digest than carbs. Carbohydrates are the most efficient fuel for your body, and complex carbs break down slowly, providing sustained energy which is important for any survival situation.

I think the ideal survival food should have mostly complex carbs, with plenty of fat and very little protein.

It is true that protein alone is not such a grand energy source for consumption, but it is necessary to support the metabolic process, and the enzymes and catalysts (like Cytochrome-P-450) cannot be supported with a diet that contains several amino structures. There's also the issue of catabolysis of muscle tissue, which no amount of carb intake will mitigate. I include protein because it is necessary for the other two sources to work right.

Enzymatic processes between amino and oleic acids really are the regulating elements of the digestion process, and the assimilation of simpler compounds for cellular health. Carbs break down to simpler carbs, such as clycogen, which support the anaerobic process in muscle tissue, or they are converted to fat by enzymes. Since the body can only store about a two day reserve of carbohydrates (mostly in the form of Glycogen in the liver), the balance of carbohydrates must be converted to fats to be retained or it is lost.

Conversely, fats are fairly easily broken down into usable oleic acids, when proteins are included in the diet, provided the carbohydrate consumption is not very high (carbohydrate intake stimulates insulin production, which interferes with the digestion of fatty acids and proteins). Bile is an efficient and abundant enzyme in our systems made just for the purpose of digesting or breaking down fat and protein into cellular food. It is the top performer in our digestive process, responsible for liberating nearly 80% of the available energy from the food we eat. While a certain amount of carbohydrates are necessary for balancing the absorption and utilization of nutrients (anyone who's experienced the Atkins diet understands that without carbs, the body will not retain fat, no matter how much is consumed), it is almost exclusively fatty acids that feed cellular tissue under nominal activity levels. The protein is there to keep the cellular processes going and to keep the enzymatic levels balanced for all digestion and absorption. Take away the protein, and you will lose muscle tissue regardless of how much fat or carbs you eat, and your health will deteriorate quickly.

I would give up the carb loads long before I would think about losing the proteins. Even if it isn't animal based, I know I can last longer on a nut and legume diet than I can on a sack of potatoes or rice weighing double or more. In a snack balancing act, I would look for a high fat content first, with the carbs and protein content at least equal to each other. I don't think it matters much what form the carbs are in, simple or complex, other than simple will be more efficiently utilized. What makes complex carbs last so long is the amount of work the digestive system has to do to convert them into a usable form (either sugars, or fats). Since the end product of complex carbs is the initial goal in my diet, I would prefer to take the short cut to get there.

Something else to note, my experience is that carbs don't do a great deal for satisfying my appetite. They can taste good, but I don't reach that "Had enough" point with them like I do eating fats and proteins. I can eat about a half a cup of pemmican and not feel hungry for at least 4 hours, even under moderately rigorous activity. I can eat half a dozen whole wheat pancakes with syrup (roughly three cups of food), and two hours later my appetite is peaking again. (not that I'm recommending pemmican in this thread mind you, just citing it for comparison purposes <img src="/images/graemlins/grin.gif" alt="" />)

However, in a survival situation, I'll take whatever I can find. There's no such thing as too much.