system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what is fat in the human body? Is it in a cell?

When you lose weight do the cells die? If the cells don’t die, how long does it take? Minutes, days, weeks? Nothing seems to discuss how fat is stored in the human body except to say that it is....  Thanks!
gpt
The fat is stored in specialized cells named "fat cells". They absorb the fatty acids that are hanging about in your blood and prepare them for long-term storage within themselves. 

When you need the fat they convert the fat in to something the body can use, like the fatty acids and sugars, and release them in to the bloodstream to be used by the rest of the body. 

The cells don't die, they simply get smaller as they store less fat. You can think of fat cells as unusually complicated containers of fat. When you're eating, they get bigger. When you stop eating, they get smaller.