Indeed, while it may not always function at optimal levels (for a variety of
reasons, including genetics), it still tries to do its very best. The body, for
all of its limitations and so forth, is not a lazy thing!
With this in mind, the body is always trying to keep is alive and functioning
in the manner that it deems to be healthiest.
And that’s why if you suddenly decrease the amount of calories that you
need, your body won’t try to do more with less. In other words, your body
won’t respond in the way that you want it to: it won’t necessarily provoke
catabolism and thus reduce weight and fat cells.
Instead, your smart and wise body will try to keep you alive by slowing
down its metabolism. It will simply believe that something is wrong –
maybe you’re trapped somewhere without food – and it will just begin to
become very stingy with energy.
So what’s the end result? If your body needs 2000 calories a day to
survive, and you suddenly give it only 1000, it won’t begin to burn off 1000
calories worth of cells that you have lying around on your love handles.
Instead, your body will slow down its metabolism. It will really try and
get as much energy out of those 1000 calories, because it doesn’t want to
waste anything.
Physically, you’ll naturally feel more tired because your body is being very
miserly with energy, and will devote its 1000-calorie ration to essential
systems, like blood and oxygen supply (and others).