system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: why is it so difficult to go a week without eating when we have 10s of thousands of calories worth of body fat?
gpt
Just burning the fat reserves you have **might** keep you alive a bit longer, but it certainly isn’t going to do anything when it comes to replenishing the vitamins and minerals that your body depends on. No sodium or potassium? Goodbye muscle functions. 

Your body keeps telling you that it’s hungry because it depends on a lot more than just calories to survive.