Why do overweight people lose weight quicker than a regular size person trying to lose weight?

To lose weight, you have to burn more calories than you consume. Larger people burn more calories than people who weigh less, even if they're just sitting around. Someone who weighs 280 pounds can maintain their weight by eating 2400 calories a day. If they cut down to 1400 calories a day, they're eating 1000 calories less per day than they need. But if someone who weighs 130 pounds burns 1600 calories per day just by sitting around, and they cut down to 1400, that's only a deficit of 200. It will take the smaller person longer to lose weight, because their calorie deficit is smaller.