Why is this the answer?

The answer is bellows because this clever riddle uses fun word pictures to describe a special tool that helps make a campfire or fireplace much hotter. A bellows is like a simple air pump that is a true friend to any fire. Fires need lots of air to grow and stay burning, and a bellows helps give them exactly what they need to get big and warm. The first part of the riddle says, "When fat, my body fills with wind." Think about what happens when you pull the two wooden handles of the bellows apart. The big leather part in the middle opens up wide and gets nice and "fat," and it sucks in a whole lot of air. It is holding the "wind" inside its body, just like your lungs when you take a big deep breath before jumping into a pool. The riddle continues with, "When pushed to thin, through my nose I blow." After the bellows is full of air, you squeeze the handles back together quickly. This action makes the leather middle part go flat and "thin." All that air that was trapped inside is forced to rush out very fast. The air blasts out through the little metal spout at the end, which the riddle cleverly calls its "nose." This blast of air is the most important part of the job. Finally, the clue says, "Then you can watch the embers glow." If a fire is starting to die down and only has a few small, red, faint pieces of wood called embers, that strong blast of air from the bellows is like a tiny, powerful wind storm. The extra air makes the embers get super hot very quickly, making them turn bright orange and start burning with big, new flames. This is exactly how the bellows helps the fire come back to life and grow big and strong again.