system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we get hungry if we have excess calories already stored in our body. 

If our body stores excess calories as fat cells, why do we get hungry again when our body could instead burn off some fat cells first which would also reduce health problems associated with carrying too many fat cells?
gpt
The short answer is evolutionary history - it's only been in the last few thousand years (arguably the last thousand) that we've had an abundance of food.  Before that, we were just like other foraging animals - we had to constantly be looking for food. Because of this, it would be entirely possible that we may have to go days, even weeks with little to eat if the food supply was short.  Essentially, our bodies wouldn't want to "waste" the fat we have stored up - it would be better to save it for when we really need it.  Hunger likely evolved as a way to ensure a constant supply of food when it was available so fat stores could be saved for dire circumstances.