Why Starvation Mode?

No, this is not a thread about starving myself or anyone else. Instead, I am curious as to why starvation mode even exists. What evolutionary purpose does it serve? If our bodies can survive on fewer calories, then why don't they? 

This is just my speculation, but does it have something to do with nutrient intake? For example, if you have 2000 calories per day as opposed to 1000, then you are more likely to have a higher nutrient intake...I think.

I don't really know, which is why I am asking. If anyone happens to have the facts, that would be great. However, further speculation is also welcome.

I've always been curious about this myself... here's some great information from another CC member:

http://caloriecount.about.com/truth-starvatio n-mode-ft28742

hope it helps!

being able to survive on fewer calories comes in handy when it's winter and food isn't plentiful.

But that puts a strain on the body, and it takes essential nutrients from some areas and puts them where its most needed.

for example, how your body reacts to fight/flight - the blood rushes to your brain, away from your hands and feet and digestive organs. you still NEED it in those areas, but for this moment, its most beneficial to have your brain and senses heightened.

so when its NOT necessary to be super-efficient, the metabolism goes back up so that ALL your body's processes can work to 100%, instead of skimping.

/speculation

Original Post by crazydiamondchrysalis:

being able to survive on fewer calories comes in handy when it's winter and food isn't plentiful.

But that puts a strain on the body, and it takes essential nutrients from some areas and puts them where its most needed.

for example, how your body reacts to fight/flight - the blood rushes to your brain, away from your hands and feet and digestive organs. you still NEED it in those areas, but for this moment, its most beneficial to have your brain and senses heightened.

so when its NOT necessary to be super-efficient, the metabolism goes back up so that ALL your body's processes can work to 100%, instead of skimping.

/speculation

That's an excellent explanation (even if it is speculation). Makes sense to me ;D

For most of human history, the majority of people were in very real danger of not getting enough to eat, and our bodies evolved to adapt to environments where starvation was a definite possibility. Too much available food is a very recent phenomenon that human bodies haven't had time to adapt to.