Let's say you heat your house with a wood fireplace. Every day, you get a wood delivery that is just enough to feed the fire to warm your house. One day you decide to buy more wood than you need. First you make the fire a bit bigger to use more wood, but it's not enough. So you start storing the extra wood in your living room, then kitchen, and then you start adding more rooms to your house to fit all the unused wood.
That's kind of what your body is doing. It's not "useless" fat. The fat acts as an energy store so you can survive longer in times of famine. If you don't diminish your energy intake or use more energy through exercise (make a bigger fire), you will keep storing more and more fat.
hillsanddales t1_j20sgmt wrote
Reply to ELI5: What are the consequences of overeating? by Smart-Veterinarian11
Let's say you heat your house with a wood fireplace. Every day, you get a wood delivery that is just enough to feed the fire to warm your house. One day you decide to buy more wood than you need. First you make the fire a bit bigger to use more wood, but it's not enough. So you start storing the extra wood in your living room, then kitchen, and then you start adding more rooms to your house to fit all the unused wood.
That's kind of what your body is doing. It's not "useless" fat. The fat acts as an energy store so you can survive longer in times of famine. If you don't diminish your energy intake or use more energy through exercise (make a bigger fire), you will keep storing more and more fat.