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Anonymous
>>167947
The thing you have to consider is the AVAILABLE energy in the food, not just the chemical energy that is technically present.
For example, yes, there IS a lot of energy present in, say, grass or grain. But, to a human that energy is useless. Human beings can't digest that kind of roughage. On the other hand, we CAN digest meat very well.
Suppose you found yourself in the middle of a field somewhere, surrounded by wheat. You could spend all day picking and chewing, but all you'd be doing is wasting your fat reserves chewing away on something that you can't digest anyway. On the other hand, if you found yourself a mouse, rabbit, or some insects and you ate those instead, you would live.
You have to look at the whole scenario: How much energy/nutrition is present. How much of that is actually useable by a human? And how much effort does it take to get at that nutrition?
For example, humans can get some nutrition out of wheat when it is processed, for example, baked into bread. But grinding the wheat, separating the chaff, and cooking the bread all requires energy--turning the grindstone, sorting the wheat, heating the oven, and so on. The process is net negative. It takes more energy to do the process than you get out when you're done. The only solution is to use other resources to do the work (for example, burning wood in the oven and using machinery to drive the grindstone).
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