In school I was taught that you when you eat something on you only get 10% of the energy because 90% percent is used, looking for the food or other things. If this is wrong an explanation would be awesome.
In: Biology
That is generally pretty true when you look at the caloric intake at each level of a food chain.
Say we have a simple food chain of some grasshoppers, a carnivorous rodent, and an eagle. Say the eagle needs 1000 calories per week to survive. In order to get that, it eats those rodents’ meat. Let’s say each rodent only has 100 calories of meat to eat, so the eagle has to eat 10 of them per week to survive.
Now here’s where that 10% comes in. Each rodent has to have eaten enough grasshoppers to grow to the size it did. For each calorie of meat it has, about 10 were eaten to get there. So a 100 calorie rodent has probably eaten 1000 calories of grasshoppers. And each 10 calorie grasshopper has eaten 100 calories of grass.
So in this example, an eagle are 10 rodents to get 1000 calories. But that pack of rodents ate 10,000 calories of grasshoppers get to that size. And the swarm of grasshoppers had to eat 100,000 calories total to get to the size needed to feed 10 rodents for their lifetime.
It’s inefficient, right? That’s why there’s so much hubbub about cutting meat out of our diets; for every 100 calorie serving of beef, the cow that it came from ate about 1000 calories worth of feed. (For me, I reduce my meat intake in order to reduce the waste. But… They’re just too tasty to cut out entirely.)
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