It is said that there are about 3500 calories in one pound of fat.
If the number is correct, you would gain one pound of fat by consuming about 3500 calories, and lose 1lb of body fat by burning about 3500 calories.
So fat people should stop binge eating to reduce calorie intake and do cardio workouts to expend more calories if they want to get slim.
Because of decreasing eating can help lose fat, some people would try to starve themselves to cut down calorie intake, but it is a little complicated, it is not as simple as 3500 calories equal to 1 lbs of fat. You had better consult a fitness professional if you want to lose fat by dramatically decreasing your eating.