If you are not a regular contestant in competitive eating, change your habits and eat slower. This will allow your stomach and digestive system to release hormones to tell the brain that you are full.
Otherwise, you could be consuming unnecessary calories when your stomach could not react to the amount of food that was rapidly inhaled. This is another reason why fast food leads to obesity.
Eating slower gives the body and mind time to react accordingly. You simply do not need the extra calories, and your body will tell you by making you fat.